This is a 2005 twin study on orgasmic function in women which produced some very interesting data. I know lack of orgasmic function and asexuality aren't the same thing, but the two sometimes go together and interact. I also think this stands as a worthwhile reminder of just how ubiquitous sexual variation and "dysfunction" is in human populations. I have my own theories about this but I'll go into that later.
Abstract wrote:Orgasmic dysfunction in females is commonly reported in the general population with little consensus on its aetiology. We performed a classical twin study to explore whether there were observable genetic influences on female orgasmic dysfunction. Adult females from the TwinsUK register were sent a confidential survey including questions on sexual problems. Complete responses to the questions on orgasmic dysfunction were obtained from 4037 women consisting of 683 monozygotic and 714 dizygotic pairs of female twins aged between 19 and 83 years. One in three women (32%) reported never or infrequently achieving orgasm during intercourse, with a corresponding figure of 21% during masturbation. A significant genetic influence was seen with an estimated heritability for difficulty reaching orgasm during intercourse of 34% (95% confidence interval 27–40%) and 45% (95% confidence interval 38–52%) for orgasm during masturbation. These results show that the wide variation in orgasmic dysfunction in females has a genetic basis and cannot be attributed solely to cultural influences. These results should stimulate further research into the biological and perhaps evolutionary processes governing female sexual function.
Essentially, you have over 20% of a female sample reporting never or almost never having an orgasm even while masturbating. That represents a huge chunk of the population, and the study finds that it's as genetically linked as traits like blood pressure and age of menarche. This goes up against a huge amount of conventional wisdom. Can we believe that 10-20% of women are simply genetically non-orgasmic? What are the implications?