Well, OK, yes, we knew that in the most obvious sense, the plumbing arrangements for example.

And around here we’ve pretty much absorbed the idea that on average men and women are different: that we expect to find more men among the systemisers, more women amongst the empathisers. OK, but now the underlying causes of these differences have been clarified a little for us:

Hundreds of genes that are switched on and off differently in the male and female brain have been identified, suggesting that many patterns of behaviour regarded widely as typical of each sex could be founded on nature as well as nurture.

Note that no one is suggesting that nurture (or societally imposed gender roles if you prefer) has no influence: the general Western preference of pink for girls and blue for boys is just that, a purely Western social preference, one not repeated in other societies.

Professor Baron-Cohen said: “This is a very original study, testing which genes are expressed differently in males and females across different primate species. It confirms the supposition that genetic sex differences are expressed not just in the secondary sexual characteristics in the body, but in the brain.

“Finding genes that are conserved across species points to the evolution of these genetic sex differences, and finding them in the brain suggests that they may in part influence the way the mind works, and in part influence our behaviour.”

That we’re also finding the same genes being differently expressed across our close cousins, the other higher primates, also leads us to thinking that this is something much wider than just societal preferences.

But I think the part of it that interests me so much about this research is that given the mechanism that’s being posited, we can also explain our thoughts about why some men have the “female” brain and some women the “male”.

All the genes are there in both sexes: this male brain idea isn’t specific to the possession of a Y chromosome: it’s more about how those genes that are present are switched on (or not, of course). So the differences don’t come at the moment of conception: rather, they come during development in the womb. And this is indeed where we think the differences between Baron-Cohen’s systemising and empathising brains come from too: from fetal exposure to testosterone.

It simply looks that the original theory is being bourne out by all this later research, doesn’t it?