The researchers mailed questionnaires to 3,654 pairs of female twins ages 19 to 83.
LOS ANGELES TIMES
A woman's ability to experience orgasm is significantly influenced by her genes, according to a scientific study of thousands of twins published online Wednesday by the British journal Biology Letters.
The study found that genetic factors accounted for 45 percent of variation between women in the ease of orgasm from masturbation, with the rest due to differences in environment.
Variation of orgasm during intercourse was also genetically influenced, although less so -- 34 percent was due to genes.
The researchers from London's St. Thomas' Hospital and Keele University in Keele, England, mailed questionnaires to 3,654 pairs of female twins ages 19 to 83.
Each woman was asked two questions: "Overall, how frequently do you experience an orgasm during intercourse?" and "Overall, how frequently do you experience an orgasm during masturbation by yourself or a partner?"
The women replied on a seven-point scale that ranged from "unsure/never" to "always."
Of the 4,037 women who returned the questionnaires, 32 percent reported they never or rarely experienced an orgasm during intercourse and 21 percent said they never or rarely experienced one through masturbation.
These frequencies are in line with other surveys of women's sexuality, said Dr. Tim Spector, director of the Twin Research Unit at St. Thomas' Hospital and the principal author of the study.