A child that can’t stop hugging people, has no fear of strangers, and loves everyone equally—sounds beautiful, right?

Not always. People with Williams syndrome, a rare genetic condition, face problems every bit as challenging as those with autism, from learning difficulties to trouble forming friendships. As Jennifer Latson reveals in her moving book, The Boy Who Loved Too Much: A True Story Of Pathological Friendliness, it can also be immensely difficult for parents.

The syndrome, whose sufferers have a surfeit of oxytocin, aka the love hormone, affects roughly 1 in 10,000 people worldwide, with 30,000 in the U.S.

Speaking from her home in Texas, Latson told us how one Williams patient in particular, "Eli D’Angelo," changed her life.

Most of our readers will be familiar with Asperger’s or autism. But like me, I suspect, few will have heard of Williams syndrome. Give us a quick 101.

It’s sometimes called the opposite of autism, although there are overlaps. People with Williams tend to love and trust everyone, so they run up to strangers and hug them, which obviously, also makes them very vulnerable.

It was identified in in the 1960s in New Zealand by John Williams, a cardiologist who noticed a lot of his patients had the heart condition supervalvular aortic synosis. It’s very rare except in people who have Williams syndrome.

Williams also noticed that several patients had a similar personality and distinct facial features. Williams sufferers tend to be elfin-looking, which was why the disorder was originally called elfin facies syndrome. They have narrow chins, prominent ears, high cheekbones, and upturned noses.

It is caused by a very small genetic deletion, about 26 to 28 missing genes on chromosome 7. There are some serious symptoms, like intellectual disability, heart defects, and gastrointestinal and muscle tone problems. Developmentally, it’s similar to Downs syndrome. On average, IQ tends to be around 50.

Your book focuses on an American boy named Eli D’Angelo, a pseudonym to protect his identity. Introduce us to him—and tell us how the syndrome manifested itself.

I met him when he was 12. He was so warm and friendly; he hugged me several times as soon as we met. At the end of the evening, as I started to put on my coat, Eli said, 'Wait! You’re leaving?' In the time I had been there, we’d obviously become best friends. He thought I would spend the night, or move in forever. [Laughs.]

People with Williams don’t tend to be good at reading social cues. They don’t know when you want to end a conversation or leave. Eli also had trouble connecting, conversationally. He had a set repertoire of questions so he would always ask, 'Do you have a dog? Where’s your Dad? Do you have kids?' His interests are similar to people with autism. He’s fascinated by anything that spins: ceiling fans, pinwheels, and, above all, floor scrubbers. [Laughs.]

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You write, “One of the heart-breaking hazards of raising a kid with Williams is that your child loves you intensely and unconditionally, but he feels the same way about his bus driver.” How did Eli's mother, Gayle D'Angelo (also a pseudonym) cope?

It was an uphill battle. Since Eli was seven, she has been a single mother. And Eli’s impulsivity was so strong that it seemed that, no matter what, he was going to keep hugging people. He knew it was wrong and would apologize as he was reaching out to hug a waitress or a stranger. He’d say, 'I’m sorry, Mom,' then do it anyway.

Her impulse was to protect him at all costs. She didn’t want him to be exploited or taken advantage of, so she barely let him out of her sight.

Her other fear was that, as he became an adult, if he were still throwing himself at people and smothering them with affection, it would be a lot less endearing in a grown man than a little boy.

It became particularly problematic when he turned 13. Eli didn’t have the extreme self-consciousness and body shame the rest of us have during our teenage years. He would walk around with an erection, not understanding that anything was unusual about that.

Williams syndrome results from a few missing genes. Talk about the neuroscience experiments being done on Williams Syndrome at the Salk Institute—and the role of oxytocin.

That is fascinating! At the Salk Institute, they've been trying to narrow down which genes contribute to which symptoms in Williams. Their original hypothesis was that all symptoms and traits depend on the interplay between multiple genes. There’s not one gene that causes eye color; it’s multiple genes interacting. So not every person with Williams is missing the exact same 26 to 28 genes, although 99.9 percent of them are.

They happened to come across a girl who had tested positive for Williams and had a lot of Williams traits as far as mental disabilities, health issues, and facial features. But she didn’t have the same overwhelmingly friendly, outgoing personality. They drilled down and found that she was missing all the Williams genes except for one, which seemed to be correlated with the friendliness part. That was groundbreaking.

Scientists realized it was related to the levels of oxytocin. They knew that oxytocin is involved in social/intimacy behaviors, like mother-child bonding or romantic encounters. And they found that people with Williams syndrome have a lot more oxytocin than everybody else, and that it fluctuates wildly in the brain. As a result, they feel this biological impulse to love all the time. (Read how oxytocin may help people with autism.)

One of the surprises for me was your theory that Shakespeare’s fools—and even elves—may have had Williams syndrome.

Before modern science existed, it was a more magical way to explain why someone seemed so different. They know that a lot of fools in medieval courts had a disability, because there are historical records that show somebody was being paid as a caregiver. They didn’t know what Williams syndrome was back then. But we can assume, if you were going to pick someone for their ability to be a good storyteller, very funny and good with wordplay, these traits would be common to Williams syndrome. But it’s an educated guess.

A fascinating discovery is that Williams sufferers are, to quote Oliver Sacks, “a hyper-musical species." Why is there this special affinity with music—and how did it manifest itself in Eli’s case?

There was a study from Vanderbilt University that Eli took part in, trying to determine if there actually was a higher tendency for people with Williams to have perfect pitch or be musical savants. Some say people with Williams are more likely to be gifted musically than the general population, but others contradict that. It’s not totally clear. What is clear is that people with Williams are driven by music. They respond strongly viscerally to a sad song; they start crying or, if they hear an upbeat song, they'll be dancing.

That’s true for Eli. Anytime he’s not talking, he’s singing or humming or doing something rhythmic with his hands. His musical tastes seem driven by the drama of music. He really likes the singers Meatloaf, Pavarotti, and Lady Gaga.

I was also intrigued by the cross-cultural comparisons of the condition. Tell us about Carol Zitzer-Comfort’s research into Williams syndrome in Japan and America.

She found the way Williams manifests itself is the same in different cultures, but the way other people respond to it is very different. It’s less disabling in the U.S., where we value extraversion, warmth, and physical affection. In Japan, it’s considered very rude and intrusive to walk up to a stranger and hug them. So was more likely that parents would list the condition as very troubling in Japan. People with Williams [in Japan] are also more likely to be institutionalized than they are in the U.S.

Williams cannot be picked up in prenatal tests. Might that change? And for now how do prospective parents deal with the issue?

It’s not that it can’t be picked up in prenatal tests, but that it would be so expensive, because they don’t drill down to that level of rarity at this point. I think that is going to change because technology is getting more advanced and it’ll be cheaper and easier to do a test for all genetic disorders, probably within our lifetime.

There’s even talk of sterilization of people with Williams—not by the government but among parents I talked to. From a reproductive standpoint, Williams is a random mutation, so two normal parents have a 1 in 10,000 chance of having a kid with Williams. Once you have Williams, though, it becomes a one in two chance. For a lot of parents whose kids are really developmentally disabled, the concern was that, if they can’t raise their kid themselves, what would happen? It is very stressful for someone with Williams to go through pregnancy. But it’s a touchy subject because we have a terrible history of forced sterilization for people with disabilities and mental illness. People with Williams have every right to be in charge of what happens with their bodies.

You write, “despite their disadvantages, people with Williams highlight some of humanity’s best features.” Expand on that and how your time with Eli changed your outlook.

A 2010 study showed that people with Williams felt no racial bias, whereas, by the age of three, every other group shows an implicit preference for their own race. This has been part of us throughout evolution, because in the early days, if you weren’t a member of our tribe, then you were very likely to be regarded as a threat.

It’s amazing to see people with Williams approach everyone with this basic belief in the goodness of the other person. For me personally, as an introvert who is more wary of new people than average, watching Eli approach people so openly was uncomfortable because I’m thinking, 'Oh my gosh, you’re taking such a risk, you’re in so much danger!' But 99 percent of the time, the person would respond positively. Watching him taking risks that I would never take, and it turns out OK, that changed me a lot.

It’s not like I learned any tricks on how to win friends and influence people. But I did learn that you can be more open and vulnerable. And that you can gain from it.

This interview was edited for length and clarity.