clipped from: www.nature.com   

Any woman with a brother could tell you that boys can be noisy, unruly and annoying. Now it seems that women with twin brothers have an extra reason to complain: they lower her chance of getting married.

Researchers have found that women who have a twin brother are also less likely to have children than women with twin sisters.

The study¹, conducted by Virpi Lummaa, an evolutionary biologist at the University of Sheffield, UK, shows that women who shared their mother's womb with a twin brother were about 25% less likely to have children when they reached adulthood. They were also about 15% less likely to marry and, if they did have children, they had fewer of them.

"Perhaps they were not as willing to marry," says Lummaa, "or perhaps they weren't as attractive to the opposite sex."