couple of lovers hold red heart . made from plasticine

My maternal grandmother, Sylvia, was an interesting woman: She joined the Army, was part of the literati scene in New York City in the 1940s, lived in a cold water flat on Gay Street in Greenwich Village and was a prolific writer who was once employed as a speechwriter for Eleanor Roosevelt (though she complained bitterly that Mrs. Roosevelt insisted on using her own speeches).

My grandmother was also the first person in her Eastern European Jewish family to marry an outsider: A fair, 6-foot-tall, blue-eyed Irish Catholic from the Midwest who was more than 10 years her senior and towered over her diminutive frame by an easy 12 inches.

Up till now, I’d chalked up my grandmother’s unexpected choice in husbands to her generally unconventional lifestyle. But, now new research has me rethinking this notion.

Using two experiments, a new study in the journal Personality & Social Psychology Bulletin found that women with natural hormone cycles (no hormone birth control) are more attracted to potential mates who fall outside their culture, race, religion and/or ethnicity on the fertile days in their cycle–which are three days that encompass the day before during and after ovulation.

And, as a further push from Mother Nature toward exotic outsiders, women perceive these unfamiliar partners to be even more physically appealing on their fertile days than on any other day in their monthly cycle.

Which means my grandfather’s blue eyes and Catholic notions must have sent my grandmother into a tizzy once her fertile phase came around–and my great grandmother into a tailspin when my grandmother announced she was pregnant and now had to get married to the tall stranger she brought home.

So, why do we get this biological push toward partners who are so different from us during ovulation?

The study authors believe it’s a throwback to the early days of humankind when there were just small clusters of people roaming the Earth. Even though unfamiliar individuals and tribes who encroached were likely feared because they could be violent, bring disease or steal resources, they were also critical for bringing in males who could create genetic diversity, which could lead to healthier babies and help avoid inbreeding caused by isolation.

As a result, the study authors contend that women evolved to seek out mates who are genetically different from themselves and to find them more irresistible during the days when pregnancy was more likely to help seal the deal.

What’s this mean for you? The next time you’re attracted to someone who looks, sounds or lives differently than you, take a look at your menstrual cycle calendar and see if your biology is playing matchmaker. You could be surprised by how much it impacts who you desire!