I Lust for Your Genes: The Biology of Attraction

Why do we feel attraction to some people but not others? Why can we meet one person and want sweaty sex with them, whereas with another person—who may be just as physically attractive—we feel no spark at all?

We know when we feel attracted, we know when we don’t, and that’s that. But have you ever wondered what’s really going on under the hood when you meet someone and feel sexually attracted to them? Why them?

The answer may lie in our genes.

 

genes - psychnsex

Hello, Me…

You’ve probably heard the old adage that “opposites attract.” However, research doesn’t really support that idea. Not only do we tend to choose partners that share our backgrounds and belief systems, there’s evidence that we’re more likely to choose those who resemble us physically as well.

Yeah, we’re often attracted to people who look like… us.

This can mean that blondes wind up with blondes and people of similar ethnic backgrounds wind up together, but it can be far more subtle than that. For example, a couple can come from entirely different ethnic backgrounds but still share their narrow face, long nose, or tall/skinny frame; almost as if they come from similar genetic stock.

Why? For one thing, humans prefer the familiar over the unfamiliar, and people who resemble those we’ve grown up looking at (ourselves, our relatives) represent something we know. More importantly, as one study found, they represent something we trustIn many cases, we may find ourselves attracted to someone who looks like one of our parents. I could go on and on about the emotional complexities of being attracted to mother or father figures, but at its simplest, your parent represents a first love and a potential model for future relationships. Maybe this is your brain’s way of saying, “Hey, this person is one of us. Go ahead, make babies.”

Another study also offers an argument for the “keep it in the family” theory of attraction: scientists at deCODE Genetics in Iceland reported that marriages between third or fourth cousins were more likely to produce more children and grandchildren than those between completely unrelated individuals. Incest taboos and the genetic reality that incest or inbreeding can produce serious health problems will usually render us sexually turned off by close family members or even cousins. However, maybe too much genetic distance isn’t ideal either, and it’s possible that a little genetic similarity creates more attraction and healthy offspring.

genes - psychnsex

Sniff, Sniff

Looks and families aside, there’s another important influence on who you find attractive. Follow your nose.

Although humans lack the well-developed smelling capabilities of many other animals, our noses still play a role in attraction and sexuality. I’m not just talking about his Old Spice or her fruity perfume, either. Everyone has his or her own unique “scent,” and humans produce hundreds of different pheromones, naturally occurring chemicals present in our sweat and other bodily emissions; these pheromones are important in attraction.

In the “sweaty T-shirt study,” Claus Wedekind gave 44 men clean T-shirts to wear for two nights before returning them to the lab. A group of women smelled each of the shirts and then described how intense, pleasant, and sexy the odor was. The results were interesting: women preferred the scents of T-shirts worn by men with immune system genes that differed from their own.

Why does that matter? If a man and woman with different immunity genes produce a child, that child should inherit greater genetic variation in his or her immune system and thus greater ability to combat diseases. So, it’s entirely possible that that hot guy you’ve mentally disrobed has the right combination of genes that are compatible with yours, which makes him smell good to you.

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The Scent of Fertility

One major goal of attraction is clear: it’s a mechanism for sex and thus reproduction. When are both most likely to occur? During the time in a woman’s cycle when she’s most fertile… during ovulation. If smelling someone’s potential genetic compatibility isn’t strange enough, it’s also possible that a man can “smell” when a woman is most fertile.

A study by Singh and Bronstad from the University of Texas at Austin examined this by asking a group of women to wear T-shirts to sleep during both fertile and infertile phases during their cycles. Men then smelled the T-shirts and rated those worn during ovulation as more “pleasant and sexy” than those worn during the non-fertile phase. This suggests that a woman’s natural scent may prove even more pleasant at ovulation and perhaps more likely to trigger attraction in men.

Where do genes fit into this? Genes still determine a woman’s specific scent, and thus, whether or not a partner will find it enticing.

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Attraction is a complex thing; similar facial features, complementary genes, and pheromones are only part of the picture.

And of course, none of these factors can ensure long termrelationship success. That’s a whole different article.

Christie Hartman

Dr. Christie Hartman is a scientist, dating expert, and author of five dating advice books. Christie earned her PhD in psychology from the University of Colorado, where she worked as a scientist for 11 years before running off to become a writer. She has a hankering for science fiction, hiking, the desert, and strong decaf coffee. You can find her at christiehartman.com.

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