Gogannaka wondered: "How can one choose his/her parents?"

1st of January, 2009, Tanyacatherine, a member of the Kanoonline, while responding to the topic "Health and Fitness", brought forward some 10 suggestions on how one can be 'hearl and hearty'. In contributing on this matter, I, on the 6th of the same month lamented that "all of her suggestions or pieces of advice, less numbers 5, 9, and 10 were valeological" , and promised to make a professional comment on that aspect "CHOOSE YOUR PARENTS WELL".
As muslims, we know that life is being planned for an unborn child: a boy or a girl, how long he or she would live, as well as shakiyun au sa'idun. I would hereby like to say that under normal, natural physiological conditions, an individual cannot choose his parents, how conscious of the world arround is he to even have a choice?. Nevertheless, 'people of the book' think of making the undo do, by clonning a prefered human sex. Only God Can Do that. As a medical scientist, I would want to say yes, scientific progress has long explained, that the Father's genes are what determine the sex of a child (Boy or Girl).A study (ScienceDaily (Dec. 12, 2008), 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, 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 is more likely to have sons, while a man with many sisters is more likely to have daughters. The study has not 100% pin-pointed what would be.. The research involved a study of 927 family trees containing information on 556,387 people from North America and Europe going back to 1600.
"The family tree study showed that whether you’re likely to have a boy or a girl is inherited. We now know that men are more likely to have sons if they have more brothers but are more likely to have daughters if they have more sisters. However, in women, you just can’t predict it," Mr Gellatly explains. Men determine the sex of a baby depending on whether their sperm is carrying an X or Y chromosome. An X chromosome combines with the mother’s X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother’s to make a boy (XY).
The Newcastle University study suggests that an as-yet undiscovered gene controls whether a man’s sperm contains more X or more Y chromosomes, which affects the sex of his children. On a 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 parent. As demonstrated by Mr Gellatly, it is likely men carry two different types of allele, which results in three possible combinations in a gene that controls the ratio of X and Y sperm; Men with the FIRST combination, known as mm, produce more Y sperm and have more sons. The SECOND, known as mf, produce a roughly equal number of X and Y sperm and have an approximately equal number of sons and daughters. The THIRD, known as ff produce more X sperm and have more daughters.
“The gene that is passed on from both parents, which causes some men to have more sons and some to have more daughters, may explain why we see the number of men and women roughly balanced in a population. If there are too many males in the population, for example, females will more easily find a mate, so men who have more daughters will pass on more of their genes, causing more females to be born in later generations.

HOW DOES THE GENE WORK?

Genetic trees illustrate how the gene works. It is a simplified example, in which men either have only sons, only daughters, or equal numbers of each, though in reality it is less clear cut. They normally show 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), for example, a grandfather may be mm, so 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. The grandsons have the mf combination of alleles, because they inherited an m from their father and an f from their mother. As a result, they have an equal number of sons and daughters (the great grandchildren).
In yet another example of a second tree (B), if the grandfather is ff, all his children would be females, they have the ff combination 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 determines the sex of the children, so the grandchildren would all be males. 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).
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Journal reference:
1. Gellatly et al. Trends in Population Sex Ratios May be Explained by Changes in the Frequencies of Polymorphic Alleles of a Sex Ratio Gene. Evolutionary Biology, Dec 11, 2008; DOI: 10.1007/s11692-008-9046-3
Adapted from materials provided by Newcastle University.