David Crews, a psychobiologist at the University of Texas at Austin (USA), published a curious study in the journal Psychological Science that suggests that the number of sisters influences the later sexual attractiveness of an adult . What happens is that this study is carried out with … laboratory rats!
The research concludes that the greater or lesser number of females among which a male rat grows influences both his sexual behavior and the way other females respond to him when he grows up . When it is time to introduce themselves to receptive females, males who have lived with many mice spend less time on sex : penetration and ejaculation occur much more quickly.
According to Crews, the result of sibling breeding is " greater mating efficiency ." That is, the male rat needs fewer attempts and less time to achieve spawn , but its erotic appeal is also less.
It seems that the greater familiarity with the females makes the male spend less time courtship because he does not feel before an unknown world. Of course, as with all experiments with laboratory animals, it is controversial to transfer these results to humans, although some experts believe that this research can be extrapolated to our species.
David Crews affirms that the study could be applied to humans, and talks about the importance of the family and the environment in which one grows up, which does not necessarily determine the personality, but does shape it.
