No one knows what the nongenetic causes of individuality are. Perhaps people are shaped by modifications of genes that take place after conception, or by haphazard fluctuations in the chemical soup in the womb or the wiring up of the brain or the expression of the genes themselves.
As individual people, embedded in our daily lives, of course we're interested in what makes one person different from another. We've got to hire one person and not another, marry one person and not another.
But among many professional women the existence of sex differences is still a source of discomfort. As one colleague said to me, "Look, I know that males and females are not identical. I see it in my kids, I see it in myself, I know about the research. I can't explain it, but when I read claims of sex differences, steam comes out of my ears."