Men are less sexy if they grow up with a lot of sisters, according to a report published in Psychological Science. The study was performed on rats, and researchers found the gender ratio of the family of a male rat as he grows up can affect how female rats react to him as well as his own views and sexual behaviors.
Previous studies about fetus placement inside the womb, have shown that the placement of a male or female fetus can directly affect hormones of the opposite sex after birth. Additional studies have also shown that the ratio of male to female babies born, can also affect behavior of each individual or animal. One goal of this study, however, is to see how and what can affect the views and sexual behaviors of an adult based on their childhood.
For this study, researchers analyzed how many male or females were born in each rat litter. Litters were then arranged based on gender. The three gender groups were: balanced, male dominant, and female dominant. Researchers observed how the behavior of the mother differed, specifically towards the males, and then performed tests after the males grew up, specifically to measure their behavior with females.
After analyzing adult rats, researchers noticed a few interesting findings. Male rats raised with a lot of sisters spent less time mounting ‘sexy’ female rats when compared to male rats who grew up with a balanced gender makeup, or even male-dominant. However, the male rats who grew up with a lot of sisters were actually ‘better’ at mating. They performed sexual function (penetration and ejaculation) just as frequently as any other males did.
Researchers conclude how similar results may be present when looking at adults. This study helps show how the environment may play a large role in shaping the personality of a person.