Parents’ Genes, Family History do not Control Children’s Sex

Many people believe that if parents have more sons then their sons will continue having sons and so on, immortalizing the trend. However, researchers at University of Queensland (UQ), Australia, have rebuffed this notion explaining that the tendency of having boys and girls doesn’t run in families. Your parents’ genes and family history do not control your sex.

“Individuals don’t have a natural tendency to have offspring of one or the other gender. The chances are more like 51 to 49 of having a boy, but the genes of the mother and father don’t play any role,” says Dr. Brendon Zietch, PhD, professor of Health and Behavioral Sciences at University School of Psychology, The University of Queensland, Australia, and the author of the study.

In this huge research, the data was obtained from all the Swedish population registers that had every Swede individual born since 1932. It included 3,543,243 individuals and their 475,269 children. The researches linked family members and checked if the sex of an individual child was inked with the sex of their sibling’s children.

Dr. Zietch explained that there is no evidence of someone having boys or girls. “The chances are more like 51 to 49 of having a boy, but the genes of the mother and father don’t play any role. These findings have crucial implications for biological and evolutionary theories of offspring sex ratios,” says Dr. Zietch

Every couple has a 50% chance of having a baby boy and vice versa. The father’s sperm determines the sex. One half of the sperms carry X-chromosomes that assign female gender to the baby, and the other half carry Y-chromosome that give birth to a boy. The sperm that gets to the egg first is the winner and determinant of the sex of the child.

A number of myths are widely established in the society. For instance, one says that tall or rich parents have more boys than girls and beautiful parents have more girls than boys. The hormone levels at the time of conception are also given some importance.

The lead researcher explains that their findings eliminate all such possibilities and forces researchers worldwide to rethink the offspring sex ratio theory and to understand why it differs across countries.

It all comes to the lucky coincidence about gender but scientists in 2012 did a research on the Great Chinese Famine 1959-1961 and concluded that famine and shortage of food could cause the increased birth rate of daughters as compared to sons. They say that malnutrition might not be the only reason for the decline of male birth rate, a high rise in psychological and physical stress could also be the reasons for the decline.

The researcher believes that it is not possible to fully blame extreme environmental events for specific sex ratio but it is confirmed that the variation of environment faced by Swedish people born after 1932 did not affect their sex ratio of having boys or girls.

This study was published on February 19, 2020, in a journal Proceedings B of the Royal Society.

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