Scientists from the University of Michigan have discovered a genetic basis that explains why some families only have boys or girls. The identified genetic variants of RLF and KIF20B have a significant impact on the gender ratio of offspring. The results of this large-scale study were published in the prestigious scientific journal Proceedings of the Royal Society B: Biological Sciences, gazeta.ru reports.

In a large-scale analysis of the UK Biobank data, which includes the genetic information of half a million Britons, scientists have discovered a significant mutation, rs144724107. This genetic change, which occurs in 0,5% of the population, increases the likelihood of having a girl by 10%. Notably, this mutation is located near the ADAMTS14 gene, which plays an important role in fertilization processes.

The study also identified two additional genes, RLF and KIF20B, that could potentially influence the determination of a child's sex. However, the scientists stress that further research is needed to confirm the role of these genes in a larger sample.

The discovery is consistent with the well-known Fisher principle, which explains the mechanism for maintaining the balance of the genders in a population. According to this theory, when a numerical advantage of one gender arises, natural selection automatically promotes an increase in the birth rate of representatives of the opposite gender, restoring the balance.