Back in 2005, they had arrived as if stepping out of the pages of a Pottery Barn Kids catalog, twins with identical blue eyes, wavy hair, and freshly scrubbed handsome little faces. Yet even then it had been immediately clear their personalities were profoundly different. To protect their privacy, I had referred to them in print as Thomas and Patrick, so I will do the same now. At the time, Thomas was all boy, with such an instinct for roughhousing that, within minutes of meeting me, he had punched me in the arm. Patrick was more social, attuned, and sensitive, addressing me by name and exhibiting genuine interest in what I had to say. He also exhibited something else, as his mother had explained to me: behavior called childhood gender nonconformity. That meant he rejected boy-typical activities like the rough-and-tumble play favored by his brother and instead showed a strong and persistent preference for girl-typical pursuits, such as playing with Barbie dolls and dressing up in princess costumes.

I WAS APPREHENSIVE as I sat in the coffee shop, waiting for them to arrive. After all, 10 years is a long time, especially in the lives of children. Would I find that the identical twin boys, whom I had met when they were just 7 years old, had turned out the way the studies suggested they would? Would they even remember me?


The intriguing case of Patrick and Thomas figured prominently in my 2005 Globe Magazine article “What Makes People Gay?” I had chosen their story to anchor a deep dive into the research on the origins of sexual orientation because strong gender nonconformity in young boys is one of the most reliable predictors of same-sex attraction in adult males. While you might assume that boys who behave like this would grow up to be transgender, most studies have found that what tends to be different about them in adulthood is not their gender identity but rather their sexual orientation. The bulk of these boys grow up to be gay or bisexual men.

Patrick and Thomas began as genetic clones when one of their mother’s eggs was fertilized by one of their father’s sperm, and then that zygote split into two identical embryos. Upon birth, they were raised by the same nurturing parents in the same stable household. So if one of them turned out to be gay and the other straight — which their childhood behavior suggested would statistically be the mostly likely outcome — that would expose the inadequacy of the long dueling nature-vs.-nurture theories about the roots of homosexuality. How could it be either all in the genes or all in the upbringing if both of those realms were so similar for Patrick and Thomas?


A decade ago, I learned that the most promising frontier in sexual orientation research didn’t focus on genes or the environment in the traditional sense, but rather the environment of the womb. For Patrick and Thomas, that meant lots of important and potentially decisive action had likely taken place during their nine-month prenatal launchpad.

“What Makes People Gay?” became one of the best-read stories online in the history of the Globe, improbable for an article dense with science and absent any hint of a political scandal or sports championship run. Moreover, it has shown uncommon endurance. For instance, in 2012, a full seven years after publication, it ranked as the fourth most-read story of the year on the newspaper’s website.


Over the last decade, barely a month has gone by when I haven’t received an e-mail from at least one reader finding the article for the first time. These notes tend to be poignant, often coming from adolescents or their parents grappling with questions about sexual orientation, urgently Googling in search of answers. And with remarkable frequency, these e-mailers have closed by asking me variations of the same two questions: What’s changed in the research on sexual orientation since the story was first published? And how did things turn out for Patrick and Thomas?

For years, I had no new answers for them. It finally seemed like time to change that.

***

“WHERE YOU HEADED?” the Canadian customs agent at Calgary International Airport robotically asked me, barely looking up from his paperwork.

“Lethbridge,” I replied.

He snapped his neck up and shot me a suspicious look. “Lethbridge? Why are you going there?”

It was a reasonable question. I had left a city packed with the world’s leading research institutions to take a three-stop flight to an academic conference being held in an outpost of southwestern Canada that even the meeting brochure described as “a small, relatively isolated city on the southern Alberta prairies.”

But as I had learned during the last go-round, isolation is a good thing when it comes to sex research. Many academics have war stories about studies getting shut down after the local Eyewitness News team hit sweeps-week gold with a segment ginning up outrage over “how your tax dollars are being spent studying sex.”


It’s no wonder some participants in the “Puzzle of Sexual Orientation” conference at the University of Lethbridge were nervous about making an exception to their no-media rule and granting me full access. (They let me in because of the 2005 article.) Last held in 2010, the Lethbridge gathering is the successor to a conference that had taken place every five years starting in 1995 in Minot, North Dakota, an American rival for remoteness. The fact that many prominent researchers in the field do their work at Canadian universities is no coincidence. Sex research is much less of a political football in the land where they punt on third down.

The main road onto campus is Whoop-Up Drive, a nod to Lethbridge’s past as an outlaw whiskey trading post and prostitution hub. But the 50 or so researchers attending this invite-only conference are serious in their hunt for new pieces to solve the sexual orientation puzzle.

In the breakfast line on the first day, by the home fries chafing dish, I bump into Simon LeVay, who began attending these conferences 20 years ago. The British-born neuroscientist’s 1991 study, which showed size differences in a certain part of the brains of gay and straight men, had kick-started the search for a biological basis of homosexuality. The fits and starts in the field ever since have clearly tempered his expectations.


When I explain that I’ve come to Lethbridge to learn what’s changed in the last 10 years, he dryly replies, “You mean what hasn’t changed in 10 years.”

My optimism drops with the home fries falling onto my plate. But as we get into the academic presentations, my fear of a wasted trip begins to lift. There has been some real movement in the last decade, though, as usual for a field built on small, poorly funded and sometimes contradictory studies, the difficulty is in synthesizing all these fragments into a coherent framework.

Northwestern pschologist J. Michael Bailey, a well-known skeptic of male bisexuality, now confirms it’s real. Photograph by Sally Ryan/ New York Times

The difference that jumps out at me right away is the new appreciation for “fluidity.” The binary view of male sexual orientation that dominated the field a decade ago has softened. Back then, there was real skepticism about men who reported being anything other than heterosexual or homosexual. After all, lab data tended to suggest that their arousal — which effectively defines sexual orientation in men — was either to male erotica or to female erotica, but not to both. “Straight, Gay, or Lying?” was the 2005 New York Times headline that infuriated bisexuals the world over, reporting these binary results from the lab of Northwestern psychology professor J. Michael Bailey, a researcher quite accustomed to controversy.

So it’s noteworthy in Lethbridge to see Bailey present data, based on more sophisticated screening of study participants, that describes a small group of men who show clear arousal patterns to both male and female erotic stimuli. Bailey flashes a slide with the results of a subject who had been tested in the lab just a few weeks earlier. In contrast to the men who identify as “bi” but whose arousal patterns indicate they’re just on their way to gay, the man’s responses to male and female porn are virtually identical. “This is very rare,” Bailey says.

No lie: Male bisexuality is real!

That message is buttressed by data that Paul Vasey, a University of Lethbridge psychologist and one of the conference organizers, presents from his research deep in the non-Western world. Samoa, the string of islands in the South Pacific, has long had a “third gender” population of feminine/transgendered males, who are known as fa’afafine (“in the manner of a woman”). While there is wide cultural tolerance of heterosexual males having sex with these fa’afafine without calling into question their orientation (or apparently alienating their female partners), Vasey’s team documented a bisexual pattern of attraction in these “straight” men.

This modest move away from the binary view of sexual orientation suggests something of a revival of the continuum advanced by Alfred Kinsey in 1948. His Kinsey Scale offers a numerical range of 0 to 6, with 0 being entirely heterosexual (and by far most common) and 6 being entirely homosexual.

At the conference, there is a lot of talk about “Kinsey 1s,” people whom Cornell psychologist Ritch Savin-Williams refers to as “mostly straights.” While the arousal data for those who self-identify this way remains quite limited, even a skeptic like Bailey admits it is there, though he stresses that it needs to be replicated in bigger studies.

For women, researchers have for some time recognized that orientation is more complex, that arousal is harder to discern, and that, for them, orientation is about more than just arousal. Lab results have shown that women tend to show bisexual arousal patterns even if those don’t match how they report their sexual attraction. Meredith Chivers, a psychologist at Queen’s University in Ontario, mentions one intriguing and untested hypothesis: Straight women may show arousal to images of other attractive women as a “mate-guarding” response rather than being turned on. But researchers say the biggest trouble with trying to understand female arousal is the measurement tools are inadequate. Testing male arousal is easy to do: attach a device to the penis and measure size changes in response to erotic stimuli. The equivalent for women — a technique called vaginal photoplethysmography, or VPP, which measures changes in blood flow in the vagina — simply doesn’t produce signals that match up as neatly with women’s sexual attraction.

Maybe, though, these female arousal patterns are a reflection of sexual fluidity, a term that University of Utah psychologist Lisa Diamond has advanced to describe people — particularly women — who, at some point in their lives, experience attraction that runs counter to their orientation. Some critics of homosexuality who argue it is caused by how children are raised have warned that gay advocates would increase their ranks by recruiting young people to their lifestyle. Diamond rejects that theory as bunk, but says research suggests a different sort of development. “We’re not making more lesbians,” she says. “We’re making more hetero-flexible ‘Kinsey 1s.’ ”

Despite the increased acceptance of non-straight individuals, the percentage of the population that identifies as heterosexual has remained remarkably stable, around 95 percent or more. A 2011 review of nine large, reputable surveys found that about 3.5 percent of Americans identified as gay, lesbian, or bisexual.

Researchers suggest, however, that those more flexible “Kinsey 1s” or “mostly straights” likely identify as heterosexual in these types of traditional surveys. After all, that same 2011 review found that 11 percent of Americans acknowledged at least some same-sex attraction, and 8 percent reported having engaged in same-sex behavior. And for women, this growth in reports of same-sex experience has been particularly dramatic, with one British study showing it rose from 4 percent in 1990 to 16 percent in 2010.

Another group that is attracting lots of research attention in 2015, after being essentially ignored in 2005, is asexuals. Lori Brotto of the University of British Columbia tells me she initially assumed people claiming to be asexual were like the men and women she treats in her clinic for low sex drive. But the more time she spent studying them, the more she came to appreciate that they make up a distinct, if very small, category. Asexuals report no history of crushes or sexual attraction, even during adolescence, when hormones are typically raging. Also, unlike those people whose low libidos cause them distress, asexuals say that if a pill were available to give them desire, they would decline to take it.

***

ONE OF THE BIGGEST HOPES in the field a decade ago was the launch of a large molecular genetics study of homosexuality, focused on gay brothers and funded by the National Institutes of Health. Ever since 1993, when researcher Dean Hamer reported that non-twin gay brothers shared a specific region at the tip of the X chromosome, the hunt has been on for the so-called gay gene. In reality, no serious scientist expected to find a single gene responsible for homosexuality. More than 150 genes are believed to be involved in helping to determine something as straightforward as a person’s height. It stands to reason that a trait as complex as sexual orientation might involve at least that many.

The genetic explanation has always had the burden of overcoming the evolutionary paradox. Because gay men produce fewer offspring, why wouldn’t a trait for homosexuality have been wiped out by now in the Darwinian process of increasing fitness? Then again, the gay population is small, and scientists have suggested multiple explanations for why homosexuality has endured.

Making the case for genetics, even before Hamer’s bombshell, were studies of twins done by Mike Bailey and others that found homosexuality to be shared at a higher rate among identical twins, who share 100 percent of their genes, than among fraternal twins, who share about half.

But Hamer’s study was based on just 40 pairs of brothers. And other small studies, even by his own lab, failed to replicate his findings, though they did find linkage elsewhere. With $2.5 million in federal funding and a goal to study 1,000 pairs of brothers, the NIH-funded study was designed to settle that matter.

Lead investigator Alan Sanders, a psychiatrist with the NorthShore University HealthSystem Research Institute in Illinois, never got the 1,000 brother pairs he was hoping to enroll. But the 409 pairs whose DNA he and his colleagues, including Bailey, were able to analyze made their work the largest linkage study ever of male sexual orientation. It took until late last year for them to publish their findings, and by then genetic linkage studies had been eclipsed by more powerful genome-wide association studies.

Still, the results are notable. In his talk at Lethbridge, Sanders says the study found that gay brothers share genetic markers on their X chromosome, replicating Hamer’s finding on the so-called Xq28 region, as well as a more robust, statistically significant finding on chromosome 8, replicating a follow-up finding from Hamer’s lab.

The results, Sanders says, offer more solid evidence of genes’ influence on what makes people gay. But he also admits that genes likely play a lesser role in sexual orientation than the 40 percent estimate he gave me a decade ago. Now, he puts it around 30 percent, with lots of work still to be done on which genes may be involved and how. That means two-thirds of the answer will have to come from somewhere else.

And that leads me back to the area that seemed most revealing a decade ago: the environment of the womb. Here, the evidence for sexual orientation being inborn has become only stronger, though not as conclusively as I expected.

For many parents, the prenatal period is a black box — nine months of waiting, hoping for reassuring signals from the ultrasound machine and comforting nods from the technician. In reality, even identical twins like Patrick and Thomas can have very different prenatal experiences and often differ significantly in birth weight. (Patrick was 1 pound lighter than Thomas.)

Crucially, the fetal brain is being organized, with sex hormones keeping it in its default female state or sending it along the male path. Researchers have suspected for some time that the exposure to sex hormones during this organizational period plays an important role in the baby’s ultimate sexual orientation. Here there are all kinds of tantalizing clues.

For instance, otoacoustic emissions, which are barely detectable sounds in the inner ear, are believed to have their levels set prenatally and are consistently different in males and females, suggesting the handiwork of hormone exposure. But lesbians show male-type patterns.

Then there are people with a condition called congenital adrenal hyperplasia, or CAH, the result of having been exposed to unusually high levels of testosterone during the prenatal period. Adult women with CAH have higher rates of lesbianism than the general population.

That same effect of exposure to male sex hormones is believed to be at work with finger-length ratios, which are also set in utero. Men generally have shorter index fingers in relation to their ring fingers, while in women they are generally closer in the length. But lesbians typically have ratios closer to those of men.

During the Lethbridge conference, when one presenter mentions this so-called 2D:4D effect, I see the guy with a buzz cut sitting next to me, a grad student from UCLA named Matt Bramble, holding out his hand in front of him to check his finger lengths.

It turns out his ring and index fingers are closer in length. He shrugs and then cracks, “I guess that’s why I’m gay.”

In fact, despite the strength in this finding in lesbians, 2D:4D studies over the past decade have failed to reliably support the effect in gay men. And Bramble has been in the field long enough to know that the ultimate explanation for homosexuality will never be so simple. He tells me his grandfather was gay, as well as two of his grandfather’s brothers, and he’s convinced the trend will continue with a young male relative. “Something is clearly going on in my family,” he says.

Bramble, working in the lab of noted UCLA geneticist Eric Vilain, is leading a promising study of neural stem cells that could offer important answers about the interaction of genes and hormones during the very earliest fetal stages, even before the period when sexual differentiation has traditionally been thought to begin. His study focuses on epigenetics — how genes are expressed, or turned on or off. Think of epigenetics as your grandmother’s tattered recipe card for banana bread. Like the DNA sequences, the ingredient list remains unchanged. But Grandma includes instructions, such as when to fold in the bananas or when to cut back on the baking soda. And like Grandma’s annotations, these epigenetic instructions can be passed down from generation to generation without ever changing the DNA.

Vilain, who at one point in the conference had joked about being so frustrated with the slow progress that he was considering retiring, later tells me how excited he is about this work with Bramble. “This research has the potential to unlock key gene expressions that occur in the early developing brain,” he says, getting us “one step closer” to understanding how hormones are capable of programming that developing brain in ways that can alter human sexuality.

The evidence about orientation being inborn that I found most persuasive a decade ago involved children born with disorders of “sexual differentiation.” For the last four decades of the 20th century, genetic boys born in the United States with a severely inadequate penis or who had lost their penis during surgical accidents were typically castrated and their parents instructed to raise them as girls.

But William Reiner, a psychiatrist and urologist at the University of Oklahoma, told me in 2005 what he had found after evaluating scores of these cases. Even though these individuals were raised as females, Reiner hadn’t found a single one who reported being sexually attracted to males. It would be hard to design an ethical experiment that could more clearly demonstrate how nature trumps nurture when it comes to sexual orientation.

During a recent phone call with Reiner, he tells me that he has since learned the sexual orientation of more of these approximately 70 genetic males who were raised as girls. Only one of them has reported being sexually attracted to males. “I’m more convinced than ever that sexual orientation is built-in,” he says, “certainly for males.”

His sense is that something fundamental is happening when the brain is being organized. If the penis is not exposed to enough male hormone in the earliest part of pregnancy, he says, it will never function normally, no matter how much hormone it is exposed to later on — even if it becomes normal in size. “But the brain might be less persnickety,” he says. “The brain seems to be sensitive to male hormone over a longer period of time than the genitalia.” A simple “ripple in the system that shouldn’t be rippling,” he says, or an epigenetic difference in one small part of the brain might result in that part of the brain remaining female — with female-type sexual attraction to males — while the rest of the brain becomes male.

Finally, the indicator that has become more and more robust over the years is the so-called fraternal birth order effect, or FBO. In 1996, Canadian researchers Anthony Bogaert and Ray Blanchard showed that the more older brothers a man has, the more likely he is to be gay. If a man with no older brothers has a 2 percent chance of being gay, that number scales up with each older brother, so that a guy with four older brothers would have a 6 percent chance of being gay.

In the two decades since, that finding has been consistently replicated cross-culturally, and numerous alternative explanations for the effect have been ruled out. It’s about as solid an effect as any in this often murky world of sex orientation research. In 2006, Bogaert, of Brock University in Ontario, scored yet another victory for nature over nurture by showing this FBO effect applies even to biological brothers who had been raised in separate households, but not to adoptive brothers raised under the same roof.

But why? He and Blanchard have offered the maternal immune hypothesis, suggesting that a pregnant mother develops an immune reaction to something important to male fetal development, and this reaction becomes more likely with each male pregnancy. They believe the mother generates an antibody that binds to a protein produced on the fetus’s Y chromosome involved in the development of heterosexual attraction, altering that piece of the differentiation process.

It’s an intriguing concept, but until recently, that’s all it has been.

So it’s welcome news at Lethbridge when Bogaert presents preliminary findings from a study his lab is conducting that targets several male-specific substances on the Y chromosome. Though he tells me he is not ready to elaborate publicly on these early results, the other researchers in the room are clearly excited about his presentation.

Yet even this robust FBO effect has some serious limitations. It applies only to gay men, not lesbians. And, interestingly, although gays are lefthanded at a higher rate than straights, this FBO effect applies only if the gay younger brother is righthanded. (Handedness is set before birth, Bogaert tells me, noting that prenatal images of thumb-sucking preferences beautifully match the general population breakdown of 90 percent righty, 10 percent lefty.)

Birth order hardly tells the whole story. The portion of men whose homosexuality can be attributed to the FBO effect is estimated to be between 15 and 29 percent.

So how can we integrate all of these disparate pre-birth signals into an explanation that makes sense? For help, I go back to Qazi Rahman, a psychologist at King’s College in London. When we last spoke a decade ago, he and his coauthor were just finishing their book Born Gay. He had included a question mark after that same title in his earlier research, but today he is only more convinced that the punctuation hedge isn’t necessary. “Some gay people owe their sexual orientation to the fraternal birth order effect, others to genetics, some to prenatal hormonal factors or other neurodevelopmental factors,” Rahman says, “and many to interactions between these.”

***

“We were all expecting a lot more definitive answers by now,” says University of Toronto psychologist Nick Rule. Photograph by Lucas Oleniuk

AT 4:40 ON THE MORNING AFTER the conference has ended, I’m sitting with two researchers in Lethbridge’s tiny, barren airport, sipping watery vending-machine coffee.

One researcher describes maternal rat licking behavior and then marvels at why human babies are born with fixed, sex-differentiated reproductive organs that they won’t use for a dozen or more years. Another explains how fish can change their sex multiple times in their lives, in as little as 17 days.

Overhearing this, a security guard with a bald head and a bulging stomach pipes up with a non sequitur about how the world’s most expensive coffee beans are defecated by some kind of cat in Indonesia. In my fatigued fugue, I’m pretty sure I mumbled to myself, Where the hell am I?

By the time our rattling 18-seater plane takes off and I see the glistening sun climbing up an unspoiled prairie horizon, I really do feel as though I’ve been on the frontier.

My mind returns to a conversation I’d had the day before with psychologist Nick Rule of the University of Toronto. Rule had delivered a presentation on “gaydar,” the supposed ability of people to detect homosexuality in others using a variety of cues, such as speaking voice and body movements. Rule’s study focusing on face recognition found that people who were shown photos of gay and straight people were able to identify the homosexuals at considerably higher rates than chance after seeing these images for just 50 milliseconds. Interestingly, the participants’ accuracy in judgments did not improve when they were given more time to look at the photos — and actually went down when they were encouraged to really take their time. Clearly, not all gay men have feminine traits. And during the face study, accuracy remains high even after potentially revealing characteristics like hair and eyes have been removed from the photos. While the idea of gaydar may sound like a parlor trick, Rule stresses it’s important to be aware of it, because it appears to prejudice people subconsciously in hiring and other important decisions.

Yet the insights Rule shared with me about his personal life made a bigger impression. Growing up in rural Florida, he told me, he was often asked if he were gay. Although he knew he had slightly feminine mannerisms, it was a question he resented and always answered in the negative — probably for good reason. When the one kid in his high school who had come out eventually committed suicide, Rule overheard someone say, “Good — that’s one less fag in the world.”

It wasn’t until he was a 20-year-old undergrad at Dartmouth, experiencing an intense crush on a guy on the crew team, that Rule realized he wasn’t straight. (He would first identify as bisexual before realizing he was gay.) Still, he resisted this recognition, not wanting to admit the bigots back home had been right about him.

A decade ago, Rule was a 23-year-old grad student at Tufts, engaged to his Dartmouth crew crush, and proud to be living in Massachusetts, the one state that had just made history by legalizing gay marriage. Now a 33-year-old tenured professor, he’s married to that man, and the conservative US Supreme Court has made gay marriage the law of his native land. “The world is such a different place,” he says, flashing a satisfied smile.

Yet, like so many of his fellow researchers, he is surprised and a bit chagrined that while public acceptance of homosexuality has made giant leaps, the science of sexual orientation has advanced in a series of baby steps. “We were all expecting a lot more definitive answers by now,” he says.

Even if this poorly funded and often marginalized research is incomplete and imperfect, the science it has produced has been instrumental in boosting acceptance. Surveys show that people who believe sexual orientation is innate and immutable are more likely to favor equal rights for gays and lesbians. Even Justice Anthony Kennedy, writing the majority decision in this year’s Supreme Court ruling, accepted as fact that sexual orientation is immutable, though, importantly, he didn’t hang his legal reasoning on that point.

Probably the most dramatic change in public attitudes in recent years has been around the issue of transgendered children. When I wrote my 2005 story, the concept of trans kids was such a foreign one that I didn’t include it because my editor and I agreed we didn’t have enough space for a sufficient explanation.

A few advocates who read the piece disputed my suggestion that Patrick — the identical twin whose female-typical behavior I had described — would likely turn out to be gay. Instead, they said his nonconformity — today more commonly called gender dysphoria — suggested he would grow up to be trans.

I could understand their logic, but the available research simply didn’t support it.

In 2007, the Gender Management Service at Boston Children’s Hospital began prescribing medication to delay the onset of puberty in gender dysphoric children. Before long, other institutions had followed suit. Then came the explosion of media attention.

These days, many children with gender dysphoria begin taking pubertal blockers (which have not yet been approved for this use by the Food and Drug Administration) around 10 or 12 before moving on to cross-sex hormone injections starting in the 13 to 16 age range.

For children whose gender dysphoria will persist, this aggressive treatment seems both prudent and humane. Research shows that if the dysphoria lasts well into adolescence, it’s very likely to continue into adulthood. Presumably, the earlier that person is able to transition to his or her target gender, the better the odds are for reducing elevated rates of depression and suicide.

However, there is simply no accurate way to predict which children will see their gender dysphoria persist and which ones will see it go away. Some researchers, including Eric Vilain and Mike Bailey, worry that the dramatic shift in public opinion may be persuading parents the only compassionate response is to get on the rapidly moving trans train of blockers and (effectively irreversible) cross-sex hormones and genital surgery, when that approach might not turn out to be in their child’s best interest.

More recent studies continue to suggest that most gender dysphoric kids will outgrow their gender-bending behavior — with the majority of the boys turning out to be gay or bisexual — and have no lingering gender identity confusion. A 2011 review of research published in the International Journal of Transgenderism found that, of children who exhibited gender dysphoria, it persisted into adulthood in only 6 to 23 percent of boys and 12 to 27 percent of girls.

For parents, deciding how to respond to a child’s distress about being in the wrong body can be a brutally tough call.

That’s precisely what Patrick’s mother was grappling with when I met her a decade ago.

Photo-Illustrations by Ryan Huddle/globe staff

I KNEW THEY WOULD BE A DECADE OLDER, but I wasn’t prepared for how grown-up they would look. If Patrick and Thomas as 7-year-olds had seemed like camera-ready models for a Pottery Barn Kids catalog, at 17, they look as though they would fit in fine on an ad for Abercrombie & Fitch alongside all the other photogenic teenage boys.

Trailing their mother, they stride into the coffee shop projecting that classic teenage mix of confidence and indifference. I have to be careful in my greeting, because I know their mom has been circumspect in explaining who I am. All she’s told Thomas is that I’m a journalist friend who last saw them a decade ago. He doesn’t seem particularly interested in more details. She knew Patrick would never let her get away that easily. So she had told him I had met him during that period in his childhood when he felt he was a girl. Hearing that, he had chosen to delve no deeper.

With the twins, I keep the conversation light — bouncing from school to sports to college plans. As we had arranged it, our meeting is brief, before they head off to a previous commitment while their mom and I stay to talk.

“Could you tell them apart?” she asks. “A lot of people can’t.”

In truth, although they look like virtual clones, I knew immediately who was who. I detected slightly more feminine hints in the way Patrick talked and the way he stood. (Voice tends to be the most accurate form of gaydar, clocking in with an accuracy rate of around 80 percent.)

But the signs were subtle — more subtle than when he was a child.

Back then, Patrick’s mom had allowed him to play dress-up and with Barbies at home but encouraged him not to do it in public. That seemed to work until one day when he was 6 and a school official called to say Patrick was making the other kids uncomfortable by insisting he was a girl. Worried about his safety and well-being, his mother had asked him if he could try to convince himself that he was a boy. He said he would try.

That conversation had taken place about a year before I had met him, and in that time his nonconforming behavior had significantly diminished.

His mom tells me now that it seemed to fade entirely in the year after our meeting a decade ago and never returned.

Some things hadn’t changed, though. His closest friendships had continued to be with girls, while Thomas’s were overwhelmingly with boys. As they hit high school, Thomas’s relationships with girls gave his mom little doubt that he is heterosexual. But to her, Patrick’s orientation appears to be far more unclear. When she has broached the subject with Patrick, he has shut down the conversation. That’s surely not because he fears his parents would be unsupportive, since they’ve made their accepting attitudes abundantly clear.

When his mother sees all the positive media attention about trans kids, she sometimes feels a pang of doubt about having asked Patrick to try to suppress his gender dysphoria in public. She hopes desperately that he’s not still wrestling with gender identity issues that he doesn’t feel he can discuss.

Now, with the coffee bean grinding machine whirring in the background, she asks me what I think. I tell her I’m no expert but that she and her husband seem to have handled this challenge just right.

Patrick is by all appearances happy and well adjusted, a high achiever and nice kid. Most “persisters” would have never been able to successfully suppress their dysphoria for years, so the fact that his seems to have gone away suggests he truly did outgrow it, like the majority of kids with childhood gender nonconformity do.

If the research bears out, it’s likely Patrick will be gay. There’s a smaller but not insignificant chance he could turn out to be straight. The fact that he doesn’t seem interested in discussing with his mother the sources of his romantic attraction is likely less a reflection of walled-up feelings than the typical teenage allergy to discussing sex with your mother.

Perhaps he’s decided to wait until college to wrestle with a weighty matter like his orientation. Perhaps he won’t truly realize what his orientation is until after he begins living on his own on campus.

Back in 2005, Patrick’s mother had cheered the growing public acceptance of homosexuality. “By the time my boys are 20,” she had told me, “the world will have changed even more.” They’re only 17 now, and in some ways the world for gays and lesbians is already unrecognizable from what it was during that first conversation. In three years, Patrick will be the same age that Nick Rule was when he came to terms with his sexual orientation. Something tells me that, by then, whatever questions remain in the mind of Patrick’s mother will have been answered.

More from the magazine:

Neil Swidey’s 2005 story on what makes people gay

I support hunting. So should you.

Dan Shaughnessy on why we’ll always love our one-hit wonders

How a daring football team took on Boston’s busing era

How a bartender dreamed up the Falmouth Road Race

Neil Swidey is a member of the Globe Magazine staff. E-mail him at swidey@globe.com or follow him on Twitter @neilswidey.