Sex ID

The results

Sex ID was a web survey of sexuality and mental processes.

Homosexual people are more likely to be left handed (or ambidextrous) than heterosexuals, according to scientists studying data from the BBC's Sex ID, one of the largest psychology experiments ever conducted.

This is one of a series of findings from the web survey of sexuality and mental processes, which had over 450,000 participants. Other findings include:

• Women with high sex drives are more likely to be attracted to both sexes but men with high sex drives are more likely to be interested in one sex or the other.
• When asked what traits they look for in a mate, men and women agreed on the top nine traits. However, men ranked good looks and facial attractiveness higher whereas women placed greater emphasis on honesty, kindness and dependability.
• People's ability to create a mental picture of the world around them (known as spatial processing) is affected by their sexual orientation.

The researchers who studied the link between hand preference and sexuality, Ray Blanchard from the University of Toronto and Richard A Lippa from California State University, Fullerton, also say they found that gay and bisexual men tended to have more siblings than heterosexual men. And bisexual women tended to have fewer siblings than heterosexual and lesbian women.

The Sex ID findings have been published in a special section of the academic journal Archives of Sexual Behavior.

"This is an amazing set of data – 255,000 people from across the world completed the survey," says Dr Stian Reimers from University College London. "For comparison, that's about the same size as the population of Nottingham. I haven't seen research of this magnitude before."

Reimers was lead scientific advisor to the BBC on the project.

"Scientists in many universities are still examining the data, and I think it will take a few years to fully research this gigantic dataset," says Lippa.

• After only three months of operation, 462,000 people set up a username, and 255,000 completed the entire study. Many more have since completed the survey.
• There was a near 50:50 split between men and women (47% female and 53% male).
• Most ages were well represented – several hundred people over 60 completed the study. The typical age of participants was 16-30.
• Nearly half of all participants (47%) came from the UK. The top five countries for participation were, in order, the UK, the USA, Canada, Australia and Ireland. People from over 100 countries took part.

Read more detailed descriptions of the results

Take the Sex ID test

Read about the Sex ID experiment

Sex ID frequently asked questions