Quote of the Day

Why does monogamy work for some people but not for others? Research suggests that it might have something to do with the way our brains are ‘wired.’

Consider a study in which 20 heterosexual men underwent brain scans while looking at different types of images. Some of the images were sexual, depicting couples engaged in penile-vaginal intercourse. Others were romantic, showing clothed men and women engaged in non-sexual intimacy. Yet others were neutral, depicting nature scenes or imagery of people engaged in non-romantic and non-sexual activities.

Half of the men were “highly monogamous.” They’d never had a sexually open relationship, nor had they committed infidelity. They also reported having a lower than average number of lifetime sexual partners and said they rarely fantasized about anyone other than their relationship partner.

The other half were “highly non-monogamous.” These men reported having had experience with both sexually open relationships and infidelity. They reported a greater than average number of sex partners in their lifetime and said they had a preference for having multiple partners at the same time.

The results showed that, regardless of relationship orientation, men showed substantial activation of the brain’s reward pathways when exposed to sexual images. Put another way, and not surprisingly, pretty much everyone found the sexual images to be rewarding.

By contrast, monogamous men (relative to non-monogamous men) showed substantially greater activation of the brain’s reward system in response to romantic images. The areas of the brain that were active while monogamous men were viewing romantic images were largely the same as the ones activated when they viewed sexual images.

Put another way, monogamous men processed romantic and sexual images in a similar way—and found both types to be very rewarding.

For non-monogamous men, however, they seemed to be processing romantic images in a somewhat different way. Unlike the monogamous men who just showed a general reward response to the romantic images, non-monogamous men had brain regions active that were involved in higher-order cognitive processing, suggesting that they were studying and thinking about those images.

These findings suggest the possibility that different people might be predisposed to different styles of mating based on the way their brains are ‘wired.’ In other words, perhaps tendencies toward monogamy vs. non-monogamy are rooted in brain structure.

Justin Lehmiller
August 11, 2026
Are Our Brains ‘Wired’ For Monogamy Or Non-Monogamy? – Sex and Psychology

Later in the article Lehmiller ponders whether similar findings will be discovered in women.

I don’t know about the brain activity, but I have talked to enough women to know that some have absolutely no interest in nonmonogamy and others have absolutely no interest in monogamy. One woman told me that after being married for about two years she could not stand being monogamous and divorced “a really nice guy”. She discovered sex clubs and felt “at home” for the first time. After a few years she married and tried to be monogamous again. Again, she divorced after a couple years and was back at the sex clubs. The last I heard from her, when she was in her late 50’s, she was trying monogamy again. I had to roll my eyes. How many times did she need to learn that lesson?

One woman I knew from work many years ago, wanted me to take some nude pictures of her (I knew her from working on the company newsletter together when I did most of the photography). My wife was fine with it and I took the pictures. I asked what the pictures were for. One of her boyfriends wanted them. She wanted me to keep it quiet though. Here husband didn’t know. She volunteered that she had enough boyfriends on the side for her on basketball them. She tried to get her husband into swinging (this was in the early 1980’s). She was his one and only sex partner and had zero interest in anyone else.

Both of these are very sad cases. I blame social expectations creating these tragedies. Had non-monogamous marriage options been socially acceptable, people could have figured out how they were wired before getting into a mismatched relationship.