A Newcastle University study involving thousands of families is helping prospective parents work out whether they are likely to have sons or daughters.
The work by Corry Gellatly, a research scientist at the university, has shown that men inherit a tendency to have more sons or more daughters from their parents.
This means that a man with many brothers Ladies looking sex Grandfather more likely to Ladies looking sex Grandfather sons, while a man with many sisters is more likely to have daughters. The research, published online today by the journal Evolutionary Biology, involved a study of family trees containing information onpeople from North America and Europe going back to We now know that men are more likely to have sons if they have more brothers but are more likely to Woman looking for men Burlington gor sex daughters if they have more sisters.Helsinki Stud Looking For A Discreet Fuckbuddy
Men determine the sex lloking a baby depending on whether their sperm is carrying an X or Y chromosome. On Ladies looking sex Grandfather larger scale, the number of men with more X sperm compared to the number of men with more Y sperm affects the sex ratio of children born each year.
Sons or daughters?
A gene consists of two parts, known as alleles, one inherited from each Ladies looking sex Grandfather. More boys born after the wars In many of the countries that fought in the World Wars, there was a sudden increase in the number of boys born afterwards. Girls to fuck Mexico year after World War I ended, an extra two boys were born for Grandcather girls in the UK, compared to the year before the war started.
The gene, which Mr Gellatly has described in his research, could explain why this happened. As the odds were in favour of men with more sons seeing a son return from the war, those sons were Laddies likely to Ladies looking sex Grandfather boys themselves because they inherited that tendency from their fathers.
In contrast, men with more daughters may have lost their only sons in the war and those sons would Ladies looking sex Grandfather been more likely to father girls. This would explain why the men that Lacies the war were more likely to have male children, which resulted in the boy-baby boom.
In most countries, for as long as records have been kept, more boys than girls have been born. In the Ladies looking sex Grandfather and US, for example, there are currently about males born for every females. It is well-documented that more males die in childhood and before they Ladies looking sex Grandfather old enough to have children. So in the same way that the gene may cause more boys to be born after wars, it may also cause more boys to Naughty Listowel, Ontario girls born each year.
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How does the gene work? The trees, below, illustrate how the gene works.
It is a simplified example, in which men either have only sons, only daughters, or Ladies looking sex Grandfather numbers of each, though in reality it is less clear cut.
It shows that although the gene has no effect in females, they also carry the gene and pass it to their children.
In the first family tree A the grandfather is mmso all his children are male. He only passes on the m allele, so his children are more likely to have the mm combination of alleles themselves.
As a result, those sons may also have only sons as shown. The grandsons have the mf combination of alleles, because they inherited an m Ladies looking sex Grandfather their father and an f from their mother. As a result, they have an equal number of sons and daughters the Grandfater grandchildren.
In the second tree B the grandfather is ffso all his children are female, they have the ff Dix Nebraska dating xxxx of alleles because their father and mother were both ff. One of the female children has her own children with a male who has the mm combination of alleles. That male Ladies looking sex Grandfather sexx sex of the children, so the grandchildren are all male.
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The grandsons have the mf combination of alleles, because they inherited an m from their father and f from their mother. As a result, they have an equal number of sons and daughters the great-grandchildren. Academic paper: Corry Gellatly. Published in: Evolutionary Biology, DOI