JOHN TIERNEY: Legislation Won’t Close Gender Gap in Sciences.

So why are women still such a minority in math-oriented sciences? The most balanced answer I’ve seen comes from two psychologists at Cornell, Stephen J. Ceci and Wendy M. Williams — who, by the way, are married and have a daughter with a graduate degree in engineering. After reviewing hundreds of studies in their new book, “The Mathematics of Sex” (Oxford), they conclude that discrimination is no longer an important factor in keeping out women.

They find consistent evidence for biological differences in math aptitude, particularly in males’ advantage in spatial ability and in their disproportionate presence at the extreme ends of the distribution curve on math tests (the topic of last week’s column). But given all the progress made in math by girls, who now take more math and science classes than boys and get better grades, Dr. Ceci and Dr. Williams say that differences in aptitude are not the primary cause of the gender gap in academic science.

Instead, they point to different personal preferences and choices of men and women, including the much-analyzed difference in the reaction to parenthood. When researchers at Vanderbilt University tracked the aspirations and values of mathematically gifted people in their 20s and 30s, they found a gender gap that widened after children arrived, with fathers focusing more on personal careers and mothers focusing more on the community and the family.

Yes, traditionally marriage and children make men more career-oriented, and women less so. Tierney concludes: “I’d love to see more girls pursuing careers in science (and more women reading science columns), but I wish we’d encourage their individual aspirations instead of obsessing about group disparities. I can’t see how we’re helping them with scare stories about the awful discrimination they’ll face. And I can’t imagine that many scientists, male or female, are looking forward to being yanked out of the lab to play Gender Bias Bingo.” The point, however, isn’t improving science. It’s all about providing jobs and authority for diversity specialists.