Do Sisters Make Men Less Appealing?

family brothers sisters

A study finds boy rats with sisters aren't sexually popular. What about human men?

Further proof that females across the animal kingdom prefer masculine to effeminate traits when mate-choosing, a study out of the University of Texas at Austin concluded that girl rats are less sexually excited by male rates who grew up with a lot of sisters. 

According to the study, boy rats who nestled next to females in the womb and experienced rat pup-hood with a slew of sisters had a tougher time when mating season rolled around. Put bluntly: lady rats just weren't that into them. As the study notes, the way females show interest is by "wiggling their ears" and doing something called dart-hopping. Researchers noticed a significant lack of these antics towards male rats from sister-heavy litters.

While they aren't entirely sure why—other then to conclude that boy rodents act differently when socialized with lots of females—they do say that these males are just as successful sexually. In fact, they end up spreading their seed as much as the more popular rats, just with less of the traditional courtship making them, ironically, "more efficient" when mating. 10 Secrets Men Keep From Women

So how can we translate this to humans? Are men with sisters perhaps a bit more comfortable with ladies and therefore less inclined to play stereotypical games or go big with their flirting techniques? Is this why we find ourselves friends with the guy who has a family full of women?

What about you? Have you dated or known guys with lots of sisters? Have you noticed any differences?