New publications
A woman carries the family genome
Last reviewed: 01.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Scientists at the University of Utah have presented new evidence to support a theory that explains why, in some cultures around the world where extramarital sex is common, men devote a great deal of attention and care to their sisters, sometimes even more than to their own children and wives.
Alan Rogers, a professor of anthropology and lead author of the study, suggests that in some cultures, a man's genes are passed on more through his sister's children than through his wife's children. Previously, it was suggested that a man's genes are passed on more through his sister if he fathers only one of his wife's four children.
For many years, scientists have puzzled over why sometimes all the benefits and inheritance went to the children of sisters, and not to the direct heirs of men - his own children. In the countries of South America and Central Africa, extramarital affairs are very common and sometimes a man may not know for sure whether he is actually the biological father of a child. This means that his offspring may not have his genes at all. But the fact that his sister and he have the same mother means that his genes are more likely to be in his sister's children.
Dr. Rogers developed four hypotheses that had already been used in previous studies, but he constructed them in a more realistic way.
The first two of them were based on the fact that "all women have many lovers and are subject to constant extramarital affairs." As it turned out, such a theory has no right to exist due to the underestimation of the degree of kinship by children of sisters and men.
The third assumption was that the resources invested in each child were equally valuable. These conditions did not take into account the fact that investing more in the wife's children did not necessarily mean that the man would not have enough for his sister's children.
The fourth problem was that a man's actions often depended on his wife's reaction.
Dr. Rogers ultimately concluded that the old model had not taken into account that if a man's nephews inherited fewer of his genes, they would end up with nothing, rather than some reduction in resources, as they should.
Natural selection and genetics mean that relatives, in most cultures around the world, help each other.
"All over the world, people help and support their relatives, give gifts and don't really care about passing on their own genes. Natural selection certainly played a role," says Dr Rogers.
[