The researchers found that during the fertile time of the month, when levels of the hormone estrogen are high, single women appeared more likely to vote for Obama and committed women appeared more likely to vote for Romney, by a margin of at least 20%, Durante said. This seems to be the driver behind the researchers’ overall observation that single women were inclined toward Obama and committed women leaned toward Romney.

Here’s how Durante explains this: When women are ovulating, they “feel sexier,” and therefore lean more toward liberal attitudes on abortion and marriage equality. Married women have the same hormones firing, but tend to take the opposite viewpoint on these issues, she says.

“I think they’re overcompensating for the increase of the hormones motivating them to have sex with other men,” she said. It’s a way of convincing themselves that they’re not the type to give in to such sexual urges, she said.