Posted Nov. 1, 2018.
A study of hundreds of years of family tree suggests a man's gene play a major role in having a daughter or sons. Men inherited the tendency to have more sons or daughters from their parents (Newcastle university summary).
This was shown that men inherited a tendency to have more sons or more daughters from their parents. It means that a man with many brothers is more likely to have sons, while a man with many sisters is more likely to have daughters.
The researcher involved a study of 927 family trees containing information on 556,387 people from North America and Europe going back to 1600.
Men determine the sex of a baby depending upon whether their sperm carrying an X or Y chromosome. X chromosome of father combine with the mother X chromosomes and leads to a baby girl (XX) and a Y chromosome will combine with the mother X chromosome and make a boy (XY).
A gene consists of two parts, known as alleles, one inherited from each parent. Mr. Gellatly demonstrated that it is likely men carry two different alleles, which results in three possible combinations in a gene that controls the ratio of X and Y sperm:
For more details can see the link below.
Source = Newcastle University