UCLA Twin Sexual Orientation Study
 
Identical twins are not so identical.
And that’s no surprise. Although identical twins were once one single embryo, and have the same genes, all sorts of things happen after they become two. And these things can make identical twins very different.
 
We study the biological basis of sexual orientation
in our lab at the David Geffen School of Medicine, at the University of California, Los Angeles. Our primary research is on twins where one is gay, and the other straight. But we also work with pairs where both twins are straight, and pairs where both are gay.
 
Twin studies aren’t new.
Researchers have traditionally compared identical twins, who share all of their DNA, with fraternal twins, who share half their DNA. By comparing how similar fraternal twins are to each other, with how similar identical twins are to each other, you can calculate how “genetic” a certain trait is. And although this type of research is important, it will never tells us how things work. Our study is very different.
 
We have some good reasons to believe
that some of the differences between identical twins are caused by differences in epigenetics. Literally “on-top-of-genetics”, epigenetics refers to the biological effects that regulate which genes are turned on and off at what place in time, and in our bodies.
 
We hope to find out how sexual orientation is regulated
by looking at epigenetic differences in those gay-straight twin pairs. If you think you might be able to help us out, come right in.
 
Disclaimer: don’t assume anything about the sexual orientation of the twins on the pictures above! Photos: Steven Underhill & thetwinsonline.co.uk