DAVIS, Calif. — IT’S been widely observed that in recent elections men have leaned Republican and women Democratic. A key element of that gender gap is often assumed to be a difference in attitudes to women’s reproductive rights.

The perception that men and women have divergent views on abortion has persisted over time. The line popularized by Gloria Steinem that “if men could get pregnant, abortion would be a sacrament” proposes that a male-female divide over this social issue is more or less a biological given.

The polling confounds such stereotypes. The General Social Survey, which has been tracking American opinions for decades, includes the question of whether a woman should be allowed to get an abortion if she “wants it for any reason.” In 17 of the 23 years that this question has been asked, men have answered “yes” to a greater extent than women. The average difference was about 1.5 percentage points — a small but consistent gender gap, if not the one people seem to expect.

So what is it about women that makes them less enthusiastic than men about abortion on demand? Again, the survey offers answers. Using a common statistical method, one can determine the effect of different variables on an outcome of interest — in this case, the odds that someone will agree or disagree with the question. This reveals that the difference between men and women is not, in fact, likely because of their sex, but because of other factors that happen to correlate with sex.