According to a study of hundreds of years of family trees, a man’s genes have a role in whether or not he has boys or girls. From their parents, men acquire a proclivity to produce more sons or girls. This suggests that a guy with a large number of brothers is more likely to have boys, while a man with a large number of sisters is more likely to have daughters.
A research conducted by Newcastle University involving hundreds of families is assisting prospective parents in determining whether they are more likely to produce males or girls.
Men inherit a predisposition to produce more sons or girls from their parents, according to study by Corry Gellatly, a research scientist at the institution. This suggests that a guy with a large number of brothers is more likely to have boys, while a man with a large number of sisters is more likely to have daughters.
The study included a review of 927 family trees dating back to 1600 and contained information on 556,387 individuals from North America and Europe.
“The results of the family tree analysis revealed that the likelihood of having a boy or a girl is inherited. We also know that males with more brothers are more likely to have boys, whereas women with more sisters are more likely to have girls. Women, on the other hand, are impossible to foretell “Mr. Gellatly clarifies.
The sex of a kid is determined by whether a man’s sperm has an X or Y chromosome. A newborn girl (XX) is born when an X chromosome joins with the mother’s X chromosome, and a boy is born when a Y chromosome fuses with the mother’s (XY).
According to the Newcastle University research, an unidentified gene influences whether a man’s sperm includes more X or more Y chromosomes, which changes his children’s sex. On a bigger scale, the sex ratio of infants born each year is affected by the number of males with more X sperm compared to the number of men with more Y sperm.
Do you have sons or daughters?
A gene is made up of two pieces called alleles, one of which is inherited from each parent. Mr Gellatly shows in his work that males are likely to have two kinds of alleles, resulting in three potential combinations in a gene that affects the ratio of X and Y sperm;
The first combination, known as mm, causes men to generate more Y sperm and have more sons.
The second, referred to as mf, produces almost equal amounts of X and Y sperm and has around equal numbers of sons and daughters.
The third, known as ff, has more daughters and produces more X sperm.
“A gene handed down from both parents that enables some men to have more boys and others to have more daughters might explain why we observe a population with nearly equal numbers of men and women.” For example, if there are too many males in the population, females will have an easier time finding a spouse, therefore men who have more daughters will pass on more of their genes, resulting in more females being born in subsequent generations,” explains Newcastle University researcher Mr Gellatly.
After the wars, there were more males born
Following the World Wars, the number of boys born increased dramatically in several of the nations that fought in them. In the year after World War I’s conclusion, an additional two males were born in the UK for every 100 girls, compared to the year before the war began. Mr. Gellatly’s study has identified a gene that might explain why this occurred.
Because men with more sons were more likely to see a son return from the war, those sons were more likely to father boys themselves because they acquired that trait from their dads. Men with more daughters, on the other hand, may have lost their sole boys in the war, and those sons were more likely to produce daughters. This might explain why males who survived the war were more likely to produce sons, resulting in the boy-baby boom.
More males than girls have been born in most nations for as long as records have been maintained. In the United Kingdom and the United States, for example, around 105 boys are born for every 100 girls.
Males die at a higher rate in childhood and before they are old enough to have a family. As a result, the gene may cause more males to be born each year, just as it may cause more boys to be born following conflicts.
What is the mechanism of the gene?
The trees (above) show how the gene functions. It’s a simplistic scenario in which males have only boys, only daughters, or equal numbers of each, but in reality, the situation is more complicated. It demonstrates that, despite the fact that the gene has no impact on females, they carry it and pass it on to their offspring.
Because the grandpa in the first family tree (A) is mm, all of his children are male. Because he solely passes on the m allele, his offspring are more likely to have the mm allele combination. As a consequence, those sons could have only sons as well (as shown). Because they got a m from their father and a f from their mother, the grandchildren have the mf allele combination. They have an equal number of boys and girls as a consequence of this (the great grandchildren).
The grandpa in the second tree (B) is ff, hence all of his offspring are female and carry the ff allele combination since their father and mother were also ff. One of the female offspring has children with a man who has the mm allele combination. The sex of the offspring is determined by that male, thus all of the grandkids are male. Because they got a m from their father and a f from their mother, the grandchildren have the mf allele combination. They have an equal number of boys and girls as a consequence of this (the great-grandchildren).
