Men who are more fertile come from big families

HAVING a large family could be in the genes, scientists believe, after finding that men with higher sperm quality had ancestors with more children.

Researchers from the University of Utah in the US discovered an intriguing relationship between the quantity of healthy moving sperm and the number of offspring of a subject’s forebears going back up to nine generations.

For each additional child in a family, the descendant’s sperm count increased by 1.8 million. The find suggests that coming from a long line of large families could be an indicator of better sperm, and that problems in conceiving are also inherited, even though that may seem impossible.

In a paper presented today at the American Society for Reproductive Medicine’s annual meeting in Philadelphia, the report’s authors concluded: “Genetic heritability of male factor infertility may contribute to intergenerational variations in family size.

“This is one of the first studies examining the relationship between inter- generational family size and sperm count as a marker of male factor infer- tility. We found a significant association between sperm count as markers of male factor infertility and family size, suggesting that lower sperm count is related to smaller intergenerational family size.”

Researchers looked at the sperm count of 2,182 men who had ancestors in the Utah population database going back to 1935 or earlier.

Commenting on the research, Dr Peter Schlegel, the society’s president, said: “This study shows us a clear picture of how male fertility may be inherited. Though it would seem paradoxical that male infertility is inherited, observations strongly suggest an inherited pattern of infertility.”

Previously, researchers in the Netherlands found genes can influence when a woman becomes a mother for the first time and how many children she may have, although they conceded social factors were increasingly playing a larger role in family size and timing.