Our three-year-old daughter often refuses to wear anything other than pink, and she mothers soft toys; and while our eight-month-old son has shown no noticeable preference for blue or for watching the footer with me, it's probably only a matter of time.
However, a scientific study just published in American Psychologist provides strong reasons to doubt that there are many inborn differences between genders. Janet Shibley Hyde, of the University of Wisconsin-Madison, has shown that in most cases psychological differences are small or nonexistent. It turns out that there is no difference in how good girls and boys are at maths. Girls' self-esteem is widely believed to nosedive on entering puberty; in fact, that of boys does so as well. In most respects, the genders communicate in the same way - forget all that stuff about men interrupting more and being less self-revealing.
Only a handful of the nostrums of evolutionary psychology survive Shibley Hyde's scrutiny. It's true that women can't throw things as hard or as far; they do not masturbate nearly as much, and are not up for casual shagging to the same degree; and they physically attack others dramatically less often. Taken overall the study shows that, to a very large degree, in terms of gender difference, we do start as blank slates, and it provides one of the strongest ever scientific foundations for equal-sex social policies. But then how could we ever have doubted it?
For one thing, we had children and, try as we might, could not stop our little Jimmys playing with guns, while our little Jemimas had no interest in them. Parenthood seemed so convincing (genes also appeal when explaining our brats' nastier elements).
For another, evolutionary psychology rose from the ashes of social science as free-market economics swept all before it. Books such as Richard Dawkins's The Selfish Gene were widely read and commissioners of science documentaries, notably Channel 4's Sarah Ramsden, leaped on the bandwagon. They were followed by the BBC, travelling upon the family-friendly vehicle of Robert Winston, a psychologically unqualified fertility expert happy to read out its scripts.
A common method was to show that patterns of electro-chemistry in the body or brain were different for men and women, or that various bits of brain had different sizes. That this could be due to differences in upbringing rather than the Y chromosome was rarely considered. Yet it has been clear for some time that nurture affects biology profoundly. Several studies show that women sexually abused as children have 5% less of the brain's hippocampal region than untraumatised women. Similar evidence regarding the effect of nurture exists for patterns of brainwaves or for crucial hormones such as cortisol.
Little coverage was given to a study of 37 nations that showed that the more a country fosters women's financial independence, the less they are attracted by rich men. Nor have I noticed coverage of the fact that, although women tend to be twice as likely as men to suffer depression in the Anglo-Saxon (Americanised) world, that difference disappears in much of gender-equal Scandinavia.
Thank the Lord, the rampant genetic determinism of the 80s and 90s - which also justified the rich man in his castle and the poor (relabelled as underclass) in their place - is finally waning. With Shibley Hyde's study we see potent evidence of what many may have been thinking for some time.
· Oliver James is the author of They F*** You Up - How to Survive Family Life
