Men With Male Siblings are Highly Fertile
All the ladies who are seeking a man to start a family, here is a piece of information you could use.
A new study suggests that men, who have many brothers, are more likely to be fertile. According to the study, the more the number of male siblings a man has, the brighter are the chances of the man being fertile.
The findings of the study also substantiate the theory that couples with genes for good male fertility are more likely to have boys.
For the study, researchers from the University of Sheffield assessed 500 men and compared the travelling speed of their sperm with their family make-up.
"We found the greater number of brothers rather than a sister a man has, the faster his sperm is, increasing the likelihood of fertility. Lots of brothers is also an indication that the man's parents have strong male fertility genes, and they would then be passed on to the son," Dr Allan Pacey, one of the researchers from the University of Sheffield was quoted as saying by Mail Online.
"The results are very surprising and could provide genetic insights into why some men are more fertile than others," Dr Pacey further said.
Even though the research does not suggest how male infertility can be treated, "It does, however, give food for thought about the importance of genetics for sperm motility and may open the way to more studies in this area," he added.
Sperm activity apparently is a significant factor that influences male fertility, the report says.
"We are very intrigued by this finding and hope other researchers examine their data sets in a similar fashion. If our results can be replicated we think it provides some evidence that humans have experienced what evolutionary biologists like to call "sexual conflict". The idea behind this is that genes that make males reproductively successful make females reproductively unsuccessful, and vice versa," Jon Slate, professor of evolutionary genetics at the University of Sheffield said, according to the report.
The researchers said that the findings of the study do not indicate that there is any need for men with sisters to worry about anything. Also, they said that they do not know if the same theory is applicable for women with sisters as well, and that it is much more difficult to measure the same.
"This is certainly not a smoking gun as a reason for infertility in men," lead author of the study, Dr Jim Mossman, postdoctoral researcher at Brown University in the US was quoted as saying by Mail Online.
"However, it would be interesting to test whether the same relationships are observed in other human populations as well as in other species. Likewise, would we observe similar associations when looking at female fertility? If the relationship between sex-bias in the number of children and fertility is a more universal phenomenon, then we may expect female fertility to follow a similar pattern, albeit in the opposite direction," he added.
The findings are published in the Asian Journal of Andrology.