How can a woman tell if a man will give her a big family? Just count how many brothers he has.
Research indicates men who have a lot of brothers are more fertile than other men, as determined by sperm motility.
A man’s sperm “motility” roughly refers to the speed of his sperm. The faster a man’s sperm, the more fertile he is and the easier time he will have conceiving a child.
While it takes high fertility levels from both a man and a woman to conceive quickly, researchers note it’s much easier to measure a man’s fertility than a woman’s, which explains why it’s difficult to say whether a woman with many sisters will benefit from similarly enhanced reproductive capabilities.
However, measuring a man’s sperm motility is relatively easy, and Dr. Jim Mossman, of Brown University, reached his conclusions by looking at 500 men to identify a link between motility and family makeup.
Mossman noted the study is one of the first to draw a potentially important connection between genetics and fertility, hypothesizing that women with many sisters may experience a similar boon to conception.
But Mossman suggested further research needs to be completed to determine whether the connection between male siblings and motility extends beyond humans and describes a universal pattern within nature.
Source: The Asian Journal of Andrology.
