Do Rats Reveal Why We're Gay?

A study of rats may determine whether men who grew up in predominantly female households are more likely to be gay, reports Time magazine.

Time writer John Cloud dissects a study published by Psychological Science in which a group of University of Toronto psychologists followed 88 rats to track their sexual development from birth to death. Here's the news: Boy rats who have more sisters are less reliable heterosexuals than boy rats who have fewer sisters. That's not to say having a sister makes you gay, but the boy rats with lots of sisters were significantly less interested than other boy rats in mounting girl rats.

Cloud offers two possible explanations: Male rats are less interested in female rats because they are already familiar with females or "males reared in a female-based litter may be less attractive to females because they secrete less or different odor cues."