Most women are either bisexual or gay but “never straight”, a study suggests.

Research has found that though lesbians are much more attracted to the female form, most women who say they are straight are in fact aroused by videos of both naked men and naked women.

The study, led by Dr Gerulf Rieger from the Department of Psychology at the University of Essex, involved 345 women who were shown videos of naked men and women and had their responses analysed.

The results, which were based on elements such as whether their pupils dilated in response to sexual stimuli, showed that straight women were strongly sexually aroused by videos of both attractive men and attractive women, even though they said they were only interested in men.