A survey of 3,600 people conducted by Mr. Lippa in 2006, published in the journal Psychological Science, found that heterosexual women are 27 times more likely than heterosexual men to express attraction to their own sex.

Some researchers believe we can chalk this difference up to cultural influence…

Sex researchers agree that some men do experiment, although much less frequently than women.

This is not because of culture, it’s biology, Dr. Baumeister says.

“It looks pretty hard-wired,” he says.

In a survey of sexuality studies published in the Psychological Bulletin in 2000, Dr. Baumeister found that social and cultural factors such as education and religion play a much stronger role in influencing a woman’s sexuality compared with a man’s. The relatively lower role of cultural influence on men’s sexuality is reason to believe their sexual behaviour is rooted in biology, Dr. Baumeister says.