Michael Barone‘s latest Washington Examiner column ponders potential unintended consequences from Hillary Clinton’s proposed policies for closing a perceived pay gap between men and women.

The problem is that, if patriarchally erected barriers aren’t the reason for disparate data, it will be hard to deliver on promises that things will be different if they’re battered down. Policies that are supposed to do that may turn out to have the opposite of the intended effect.

Consider last week’s front page Wall Street Journal story headlined “Women in elite jobs face stubborn wage gap,” and contain your outrage at injustices like the female M.D. who makes only $303,000 compared to her husband’s $364,000. The reporter’s suggested cure for this injustice? More men need to take paternity leave and do additional housework.

Which is to say, the gap results not from institutional barriers but from personal choices which tend to be rooted in biology. Science — we all respect science, don’t we? — tells us men and women are different. Only women give birth and, it turns out, they’re more likely to take parental leave and choose work that requires limited and definite hours — and which accordingly pays less.

Note that these decisions are being made by people who grew up when most women worked outside the home and who attended female-majority colleges and graduate schools. Such women know they have choices, and they tend to choose to trade away income for family time. That’s a rational choice, even if it means never being CEO.

Hillary Clinton’s solutions for equalizing pay — “flexible scheduling, paid family leave and earned sick days” — tend to encourage women to take time off from work, which in turn tends toward lower lifetime earnings. That’s certainly been the effect in Scandinavia, where such policies have been carried farthest. The effect, Swedish scholar Nima Sanandaji writes, is that “many women work, but seldom in the private sector and seldom enough hours to reach the top.”

The fact is that the barriers Clinton thinks are holding women back mostly came down long years ago.