XYY

Jed Bland

Issue 11
August 2000

 
Some people are born with an extra Y chromosome and the fable has been around for many years that, because of it, they are supermen, with extra intelligence and all the features that are supposed to be good in a man..

The most well-known study, in fact, claims to prove the opposite, but it is famous as an example of how things can go tragically wrong if a researcher doesn't select his subject group carefully enough.

It centred around high-security prisons and institutions in America, where it was discovered that there seemed to be an unusually high proportion of XYY men. The suggestion that XYY men might be more violent caught the attention of the press and, for a while, it looked as though totally innocent XYY people might be imprisoned 'just in case.' It turned out, on examining their records, that their crimes were civil ones, fraud and so on, not crimes of violence. They were in high security prisons because of continual re-offending, and in general came from deprived social backgrounds.

Subsequently a much more extensive survey in Denmark, on young men entering national service, showed that XYY people are, in general, not outwardly remarkable from anyone else.

There are probably millions of them. Nobody knows. Since they grow up, have children and live their lives with no-one knowing that there is anything different about them, they would do not appear in clinics. Yet textbooks still stereotype them as violent and of reduced intelligence. It reminds me of the bumble bee. Aeronautical engineers assert that the bumble bee cannot fly, yet no one has told the bumble bee, so it goes on doing it.

Clearly the NHS only carries out such tests as it cannot avoid. In America. as much testing can be done as the parents can be persuaded to pay for. Before long, someone will read a paper about the high incidence of XYY infants in American middle class families.

Are these children are being pathologised unnecessarily? Parents may be sensitised to behaviour that would otherwise be dismissed as boyishness. If you accept that intelligence tests are nothing of the sort, but predictors of academic ability, difficulties in socialisation, in the crowded and artificial environment of a school, may well lead to reduced performance.

It doesn't bode well for the future of the Human Genome Project. The map it has produced is a composite. It may well not totally correspond to any real human being, living or dead. We now have the ultimate human stereotype. Doctors will be able to discover new syndromes that can be named after them, and it's all good for business.