The reason our friends seem a bit kooky, and our mates may seem strange compared to ourselves, is that opposites attract. Right?
Nope. A large body of research suggests that we pick our friends, as well as our mates, because underneath it all they are very much like us.
So if our friends are kooky, and our mates a bit strange, chances are we are too.
And the latest study in this ongoing research takes it a little further. We can blame it at least partly on our genes. People tend to like others who have the same inheritable traits, so we often choose friends and mates who are genetically similar to ourselves.
"People prefer their own kind," says J. Philippe Rushton, a psychologist at the University of Western Ontario. "Extroverts favor extroverts; traditionalists, traditionalists."
That may not jibe with your own experience, but Rushton notes that genes are not the only players. We're not a bunch of robots that are being led around by genes that even pick our friends. Other factors, according to the researchers, play a significant role.
Rushton says our friends and our mates may also be a product of the "unique environmental effects such as being in the right place at the right time." You can't link up with an ideal mate if the two of you never meet.
Our genes, Rushton says, probably account for about a third of the reason why we pick someone else as a friend or a mate.
"But that's still pretty strong," he says. "Let's say it's a strong whisper from the genes."
This is a very different line of research from work by Rushton that has been very controversial. He claims that his research shows distinct differences between the races in intelligence (based on brain size), fertility, personality, and dozens of other variables. According to Rushton, Asians rank at the top in intelligence, with Caucasians in the middle and Africans at the bottom. Many other researchers strongly disagree.
Rushton, who has been researching the subject of friendship for 20 years, says clear patterns emerged from a study of hundreds of identical and fraternal twins, as well as their spouses and friends. It's no surprise that identical twins, who share 100 percent of the same genes, picked friends and mates who were very similar to those picked by their twins.
But here's the twist. Fraternal twins, who share only 50 percent of their genes, picked friends and spouses who are so much like themselves they could be their brothers and sisters. And, Rushton says, so do the rest of us.
"It's almost as similar as siblings," he says. "Not quite, but almost."
That "was not previously recognized," Rushton and a colleague, Trudy Ann Bons, report in the July issue of Psychological Science.
The researchers looked at a wide range of variables, including characteristics that are mostly inheritable, and those that are less so, to determine the role genes play in our social behavior. They found that "people are genetically inclined to choose as social partners those who resemble themselves on a genetic level."