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Meet the Guevedoces: The 'Girls' Who Grow a Penis During Puberty

Guevedoces are born lacking an enzyme which caused them to look like girls, while their testicles are hidden inside the body.
London, GB

Catherine (left) with his cousin Carla, both guevedoces.

Puberty is a difficult time for everyone. Some, however, have it worse than others. Jonny spent the first few years of his life living as a girl. Until the age of 11, when he suddenly grew a penis.

Jonny is one of a small group of people in the Dominican Republic known as 'guevedoces', who are born looking like girls but grow up to become men. He was recently featured in the BBC Three documentary series Countdown to Life , which explores the way in which our time in the womb impacts our lives. I spoke to the show's presenter, Dr. Michael Mosley, about his experience with the guevedoces and what he learnt while making the series.


VICE: Hi, Michael. Where did you get the idea for this series?
Dr. Michael Mosley: The first nine months of life is largely unexplored territory. Until recently, it's been quite difficult to explore but modern technology means we can visualise things much better and have a deeper understanding of what's going on. We thought it would be interesting to dive into that slightly mysterious time and look at what happens, as well as what can go wrong. It's just nine months but the things that happen then will play out for the next 30, 40, 50 years.

How did you first hear about the guevedoces?
I actually came across them when I was at medical school in the 1980s. The guevedoces were first identified by a researcher from Cornell in the 1970s. I remember hearing a talk and thinking, 'That is amazing! Can it possibly be true?' I fancied the idea of making a documentary but never found a reason. For this series I said, 'We have to do it'. It's such a fascinating story.

Does this phenomenon only occur in the Dominican Republic?
Other groups have been identified around the world. The thing about the people in the Dominican Republic is that they are very accepting, whereas in other groups these people are regarded as abnormal and badly treated. In the Dominican Republic the attitude is very much, 'Hey ho, sometimes girls turn into boys. That's the way things go.' It's remarkable how tolerant they are.

Dr. Michael Mosley

How much do we know about why this happens?
We know a lot now. It's quite strange and very compelling, the idea that you start to approach puberty and change from being a girl to a boy and grow a penis. The reasons for it go way back to the womb. We know that up to about six weeks we're neither male nor female. It's only then that, if you have an XY chromosome, the Y chromosome releases testosterone – and a particularly potent form of testosterone called dihydrotestosterone.

If you don't get that, you become a girl. What happens in the guevedoces is they lack the enzyme that converts testosterone into dihydrotestosterone, so when they are born they look like girls. They have testicles but they are hidden inside the body and they have what looks like a vagina. When they hit puberty, they get this surge of testosterone and that alone is enough to make them grow a penis and start to look like boys.


How do these children tend to cope with the change?
Quite often they have seen it in a cousin or something. It occurs in a relatively small number of families and in about one in 90 children, so they know it might happen. Quite often you have early signs. The mums say things like, 'She was always a bit tomboy-ish'. Still, they get teased. One of the boys could see why his schoolmates were a bit surprised when he went from being a girl one day to a boy the next. But on the whole there's a lot of acceptance.

In the documentary, you see the families treat the children as girls right up until the point where they start to look like boys, even when they know the change is coming.
Completely. In some cases, they decide to remain girls. They go off and have plastic surgery. They say, "What the hell, I've been a girl this long, I'll keep being a girl." We primarily interviewed people who had decided they were a boy and that's how they wanted to be. But I was aware of an aunt of one of the children we interviewed, who had decided she wanted to stay female.

What have we learnt from studying the guevedoces?
The researcher who went down in the 1970s did all sorts of investigations. She noticed that the older males didn't really have prominent prostates. With most blokes, their prostate gets bigger with age and that leads to all sorts of problems – like the inability to urinate. In fact, there is now a drug that mimics what happens naturally in the guevedoces and is used to treat benign hypertrophy (enlargement) of the prostate. It also turns out to be quite effective in treating hair loss.


Do you think the guevedoces can tell us anything about how we see gender in our society?
What it shows is how unbelievably complex it is. One of the things we explored in a later case is transgender children – boys who are convinced they are girls from an early age, and vice versa. I do think there is something genetic that happens in the womb for these kind of things and it's not an obvious voluntary or social thing.

It used to be that people would think that this was somehow a kind of mistake and you could tell them they were being foolish, but the evidence is very, very clear. When you take a child who is transgender and try to force them to stay as they are, this leads to very high rates of suicide. People are born with different urges. We can't just try to ignore that and pretend we are all the same and live according to a straightforward and obvious gender rule.

I can see why this is a prime example of how what happens in the womb can have dramatic consequences on the rest of our lives.
What you see from all this is that things kick off at various stages in the womb and they will alter your life in different ways. In the case of the guevedoces, it makes a big difference. It's a similar case to Mati's, the transgender child we featured int he show; her life is hugely shaped by something that happened very early on.

You've said that making the series had changed the way you think about gender. How?
I guess I've thought for some time that the hormones in the womb are likely to influence not just how you come out physically but also what happens to your brain. I'm not saying that men and women definitely have different sorts of brains but there's quite a lot of evidence.


I worked on a programme with Professor Baron-Cohen at Cambridge and he has this idea about empathisers and systemisers. Systemisers like data and collecting it and empathisers are more in touch with feelings. Broadly speaking, blokes tend to fall into the systemisers group and women into the empathisers. He believes, and there's quite a lot of evidence, that hormone exposure in the womb can influence that. But it's a very controversial area. Gender politics is hugely controversial, for the obvious reason that it's often being used to put down women.

What was the most surprising thing you learnt when making this series?
A whole range of things. In the first programme, I looked at the effect of diet in the first few hours of conception and what a big difference that can make. I absolutely loved meeting the family with six fingers. I was really pleased to finally make a programme about the guevedoces, something that had fascinated me for a long time. I just enjoyed meeting so many unusual and interesting people. I thought before I started it that I knew quite a lot. It turned out to be the opposite.

What do you hope people take away from watching your show?
That there is this wonderful undiscovered period of your life that you can't remember anything about but went on to shape the rest of your existence. I hope a bit of fascination and tolerance.

Thanks, Michael.

You can watch Episode Two of Countdown to Life on BBC iPlayer in the UK until the 23rd of October.