Take a look at your right hand. Is your ring finger longer than your index finger? If so, you may be more likely to seek out lots of sex partners, suggests research from the U.K.

On the other hand (pun intended), if both digits are roughly the same length, you may be genetically pre-programmed to crave one long-term mate.

Here’s why: A longer ring finger is a sign you were exposed to lots of testosterone in your mother’s womb. And that T exposure has been tentatively linked to higher rates of promiscuity, the U.K. researchers say

Make no mistake, though: “Many dozens of factors combine to affect how promiscuous you are,” says study coauthor Rafael Wlodarski, Ph.D., of the University of Oxford. Those factors range from your friendships and personality traits to your culture and environment. Wlodarski says finger length may be able to predict promiscuity when applied to big groups of people. But at the individual level, it’s just one of many variables.

While some mammals—dolphins, lions—like to play the field, others (wolves and gibbons) prize fidelity, humans fall somewhere in between, Wlodarski and his colleagues say. Finger length aside, the big news from their study is that there appears to be two distinct types of people—or “phenotypes”—when it comes to fooling around.

“There seems to be a group of males and a group of females who are more inclined to ‘stay,’ with a separate group of males and females being more inclined to ‘stray,’ ” he explains. Among men, the strayers appear to outnumber the stayers 57 percent to 43 percent. For women, the split is just about reversed.

So the idea that all men are dogs and all women crave one long-term partner aren’t supported by the research, Wlodarski suggests. In fact, his findings show that among the most promiscuous men and women, the ladies tended to act more wantonly than the guys.

Have fun talking this one over with your girlfriend tonight.