The science of why masculine men are sexy.
Source: 'Tony Fischer/Flickr Creative Commons'
Source: 'Brendan Spragg/Flickr Creative Commons'.
Source: Ebner, Riediger, & Lindenberger, 2010
In a recent study published in Psychological Science (link is external), my colleagues and I investigated whether such genetic influences might underlie female preferences for masculine faces. By measuring these influences, we would also be able to compare their magnitude against the impact of the context-dependent factors suggested by the good-genes hypothesis such as ovulatory cycle and pathogen sensitivity. To do this, we used data collected from thousands of identical and non-identical twins. Because identical twins share all of the same genes while non-identical twins only share half, we can use statistical modeling to estimate genetic effects on many different traits.
We found that the combined effect of contextual factors accounted for less than 1 percent of variation in women’s preferences for facial masculinity. On the other hand, genetic effects accounted for nearly 40 percent of the variation. This means that any differences between two women’s preferences for masculine males is more likely to be due to their genes than any of the previously proposed evolutionary contextual factors.
This doesn’t mean that contextual factors are unimportant or that genes determine whom we’re attracted to though. The majority of variation in facial preferences (around 60 percent) was still unexplained in our study, leaving ample room for alternative explanations and other environmental influences.
What we have shown here is the relative importance of genetic variation in influencing romantic preferences, and more generally, highly complex traits. It’s currently unknown whether these preferences actually push us towards partners who carry these traits. Choice of romantic partner is one of the most important decisions we will ever make in our lifetime, and the idea that our genes could influence this process has enormous ramifications. The next challenge will be explaining how this genetic variation fits into the broader story of our evolution, including how it influences actual partner choice.
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