Welcome to It’s Complicated, stories on the sometimes frustrating, sometimes confusing, always engrossing subject of modern relationships. (Want to share yours? Email itscomplicated@nymag.com.) Illustration: J.V. Aranda

After 38 years of marriage, I thought I knew my spouse. Then I got an email from the personalized genomics company 23AndMe with the subject line, “You have new DNA relatives.” Which is how I discovered that my husband Marc and I are related through more than mere marriage. We’re third cousins.

When we finally stopped laughing, we texted our 30-year-old-son, Jonathan. “I don’t know how I feel about this,” he said.

“You were the one who pushed us to get tested,” I pointed out. “You said, ‘It’ll be fun. Let’s see how much of me is Dad and how much is you.’”

“Do I need to get genetic counseling?” he fretted.

I shared my news on Facebook, with the hashtag #OurForbiddenLove. Sixty-three people quickly clicked the Like, Love, or LOL emojis, followed by a chorus of “Get out!” and “No freakin’ way!” and “How is that possible?”

“Just like the queen and Prince Phillip!”

“Or the Roosevelts.”

“You can’t make this stuff up!!!!”

This being Facebook, it didn’t take long before people started arguing.

John: “Everyone has a ton of third cousins. No one on Earth is farther apart than 20th cousins.”

Ann: “In the shtetl, we Jews all pretty much married each other.”

Doug: (mansplaining): “What Ann means is that everyone was shtupping in the shtetl.”

Kirk: “Family shrub. Very common where I’m from.”

Sharon tried to play nicely. “Maybe this explains why you got engaged so fast.”

Stacy shot back: “Yeah … cause Marc felt like family!”

Actually, he did. Marc and I met rom-com cute, on a Club Med vacation in Nassau. I was 25; he was two years older. Initially, he was chasing my roommate. We struck up an intense conversation on the plane home, and by the time we landed at JFK, I had the unbidden thought, “I could marry a guy like this.” He insisted on carrying my luggage. I saw my parents chatting with a woman I didn’t recognize, and pointed. “There’s my mother, but I don’t know the woman she’s with.”

“I do,” he said. “That’s my mother.”

“We just ran into each other,” my mother explained. Not only did our folks already know each other; I discovered I’d traveled 1,000 miles to the Bahamas, only to meet a man whose Manhattan apartment was just one block away from mine.

“We’re moving too fast,” I said to him on our first date, pulling out of a long kiss. “I think we should put the brakes on.”

It was eerie how the coincidences kept accumulating. “It’s like we’re two bodies with one mind,” he said.

He said, “We can put on the physical brakes, but please don’t put on the emotional ones.”

A man who welcomed intimacy, unlike all the emotionally unavailable guys I’d ever dated? It was intoxicating. On that same date, he read me an e.e. cummings poem because he said he loved the language: “In Just-spring/when the world is mud-luscious the little/lame balloonman/whistles far and wee….” Entranced, I quoted back, “And the world is puddle-wonderful.” It might just as well have been cummings’s famous “I carry your heart with me (I carry it in my heart),” so sure a way was it to win over my English major’s heart.

That weekend as we drove out to the North Shore of Long Island for brunch, Marc said, “Can we detour first? I want to show you one of my favorite places.”

I suddenly pictured water, weeping willows and mud. “I’m not wearing the right shoes to get wet.”

“Where do you think I’m taking you?”

“A duck pond.”

His eyes got big. “How do you know that?”

I hummed the Twilight Zone theme music and we laughed. But it was eerie how the coincidences kept accumulating. It was more than the fact that we both loved the southern gothic stories of Flannery O’Connor, or screwball comedies from the 1930s. We finished each other’s sentences.

“It’s like we’re two bodies with one mind,” he marveled.

Ten days later, we stood hand in hand in the hot summer night, watching Fourth of July fireworks over the Hudson River. Afterward, we strolled through the plaza at Lincoln Center. When we stopped to cool ourselves in the delicious mist of the fountain, he pulled me close and asked, “Will you marry me?”

“What took you so long?” I said.

“But you’ve only been dating two weeks!” my friend Pat said. “Are you crazy?”

Apparently.

Yet here we were, together four decades and two children later. Was it really possible that my beloved soul mate was also my relative? Marc and I made jokes about the movie Chinatown — “She’s my sister/my daughter/my sister/my daughter/she’s both!” — but was this a bit too Flowers in the Attic for comfort? “You’re my cousin-husband,” I said. “Better than being a sister-wife,” he said. Every time our eyes met, we cracked up laughing. Was our newfound connection romantic … or creepy?

“I’m not sure I believe it,” Marc said. “It’s not like we got this report from the Institutes of Medicine.” I saw his point: the IOM is part of the U.S. National Academy of Sciences and provides evidence-based research; 23andMe is a commercial enterprise selling ancestry and health information.

“They at least got something right,” I said. “They pegged Jonathan as our kid.” According to the report, our son shared 50.1 percent of his DNA with me. It was reassuring — but not just because it validated our saliva samples. The night of Jonathan’s birth, a nurse’s aide shuffled into my hospital room and handed me a bundle for the 2 a.m. feeding. Still doped up from surgery, I unbuttoned my gown to nurse. Then my spidey sense kicked in. I twirled the plastic name bracelet around the infant’s tiny wrist and stared woozily at it.

It said: “GIRL.”

I kept a death grip on the call button till the aide shuffled back.

“This isn’t my baby!”

She peered briefly and shrugged. “Well, it looks like yours.”

So, yes, maybe for the last 30 years there’d been just the tiniest smidgen of doubt whether the hospital gave us the right child.

What I never doubted, though, was that Marc was meant to be a dad. He’d lost his father when he was only 13 years old; having a child of his own helped fill a void in his heart. He’d been ready to start a family as soon as we returned from our honeymoon; I was ambivalent. I loved our life exactly as it was. Marc, with both a Master’s in English and an MBA in accounting, was working at a major medical center in health-care finance; I was a book publicist, and with Marc as my plus-one, went to glamorous literary events: dancing at Carl Sagan’s book launch at Area, a celebrity-studded nightclub that blazed briefly in the ’80s; swinging to the sweet jazz of the Count Basie Orchestra at Palladium; listening spellbound to legendary cabaret performer Bobby Short sing “Don’t Like Goodbyes” at an invitation-only memorial service for Truman Capote. It was the era of Bright Lights, Big City, and I felt I was at the white-hot center of the literary establishment.

It was heady stuff, but eventually I had enough. We were both thrilled when I got pregnant at 32. My doctor, who jarringly referred to me as an “elderly primigravida,” insisted we have amniocentesis to rule out chromosomal abnormalities. All went well. At 37, I conceived again, but this time the pregnancy was rocky. I bled through the first trimester. During the amnio, it took three punctures before the doctor was able to extract fluid, which triggered a cascade of contractions. The doctor ordered me home to bed rest. Terrified, Marc hovered, plying me with tea and toast. I squeezed his hand. “Sit down and listen to me,” I said. “It will be okay. This baby isn’t going anywhere. It’s a fighter.”

And it was okay. Until it wasn’t. We worried that our second son Mickey, a loving and sweet toddler, wasn’t talking. We took him for a comprehensive evaluation, expecting to be reassured. Instead, the doctor said, “Don’t expect higher education for your son.”

We knew that many marriages implode after a child is diagnosed with special needs. We were determined ours wouldn’t be one of them. “We’re still two bodies, one mind,” Marc said. Sometimes we worked so hard to give each child what he needed that there wasn’t much left to give each other. But for our 30th anniversary, we finally took our first real vacation since our children had been born. For a whole week, we savored Paris and each other, remembering exactly why we’d fallen in love in the first place.

Which is why our implausible DNA match seemed entirely fitting to everyone who knew us. It was a fun story, and we dined out on it for weeks.

Then our friend Ed emailed an article titled “No, You Don’t Really Have 7,900 4th Cousins: Some DNA Basics for Those With Jewish Heritage.” According to a 2014 international study published in the journal Nature Communications, all Ashkenazi Jews (Jewish individuals from Central and Eastern Europe) are at least 30th cousins, descended from a founding population of 350 people from the Middle Ages. We are an endogamous population, i.e., one that tended to marry within its own culture. Ashkenazi Jews share more DNA with one another than the average population does, which can skew the data. I learned about haplogroups and centimorgans and polymorphic markers. I dug deep into the technical data. With disappointment, I realized the science is not yet complete. It’s unclear if Marc and I actually share a set of great-great-grandparents or not.

What I do know is this: We’ve forged an ordinary family life, even while dealing with the extraordinary needs of an autistic child. I don’t need the imprimatur of 23andMe to tell me what I already know with bone-deep certainty: our connection is a decades’ long conversation that continues to nurture and sustain us both.

There’s an old saying that chance makes our relatives, but choice makes our friends.

Sometimes, it can even make both.