The Science of Attraction

Reinforcing information we've read before, Tamsin Saxton, Senior Lecturer in Psychology, Northumbria University, Newcastle, writes at theconversation.com about "why we were secretly attracted to people who look like our parents."

Couple or brother and sister? Teeejayy/Flickr, CC BY-SA

Have you ever thought there was an uncanny family resemblance between your friend and her partner? Or wondered for a fleeting moment whether the pair walking down the road were husband and wife, or brother and sister? You might not be imagining things.

They might actually be siblings.

Scientists have long known that species including birds, mammals and fish pick mates that look similar to their parents. This is known as positive sexual imprinting. For example, if a goat mother looks after a sheep baby, or a sheep mother looks after a goat baby, then those babies grow up to try to mate with the species of their foster mother, instead of their own.

It seems humans also “learn” from our parents in a similar way. When you ask people to judge the similarities between heterosexual couples and their parents from photos, a fascinating picture emerges. Women tend on average to pick partners whose faces look a bit like their fathers', while men often choose partners who slightly resemble their mothers. Resemblance doesn’t stop at faces – you can also see subtle similarities on average between partner and parent height, hair colour, eye colour, ethnicity and even the degree of body hair.

Fascinating

One such study of adopted women found that they tended to choose husbands who looked like their adoptive fathers.

We also know that, in general, heterosexuals are more attracted to those who resemble their opposite-sex parent than their same-sex parent. What’s more, research has shown that it’s not merely appearance that matters: it’s also about your relationship with that parent. People who report more positive childhood relationships with a parent are more likely to be attracted to partners who resemble that parent.

Remember these are generalities. Some people are attracted to people of another race, for example.

For instance, people find the very idea of sexual relationships with their siblings deeply unappealing. This aversion seems to develop automatically through two distinct processes. One process turns off attraction to those that we spend a lot of time with during childhood. The other turns off attraction to any infants that our mother looks after a lot.

Again, these are generalities. There are many people who are different from this. Where there are some generalities, clearly there is a wide diversity of attractions in the human population.

If we’re finding preferences for parental resemblance across different populations, then what is the biological explanation for this behaviour? It turns out that coupling up with a distant family member seems to be the best bet, biologically, to produce a large number of healthy children. One possibility is that if you are attracted to people who look like your parents, then chances are you may get a crush on distant relatives. This might give you better chances of more healthy children, and so this behaviour persists.