Men with Brothers Have an Easier Time Conceiving Children

C. Price

Written by: C. Price

C. Price

C. Price is part of's content team. She writes advice articles, how-to guides, and studies — all relating to dating, relationships, love, sex, and more.

Edited by: Lillian Castro

Lillian Castro

Lillian Guevara-Castro brings more than 30 years of journalism experience to ensure DatingAdvice articles have been edited for overall clarity, accuracy, and reader engagement. She has worked at The Atlanta Journal and Constitution, The Gwinnett Daily News, and The Gainesville Sun covering lifestyle topics.

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How can a woman tell if a man will give her a big family? Just count how many brothers he has.

New 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. Photo source:

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