Half of a father's sperm have all X chromosomes, half have a Y chromosome. So why
does not every family have equal numbers of sons and daughters? Why some families have
all girls, some all-boys, some a mix? Explain.
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Half of a father's sperm have all X chromosomes, half have a Y chromosome. So why
does not every family have equal numbers of sons and daughters? Why some families have
all girls, some all-boys, some a mix? Explain.
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Answer:
It all depends on the sperm cell itself.
Explanation:
Some sperm cells carry XX chromosomes and other carry XY chromosomes. Since the sperm has two different sets of chromosomes, the XX and XY, the percentage of it would be a 50-50 for either a boy or a girl. Though it is a 50-50 percent chance for a boy or a girl, it still is not balanced in some aspects. You wondered why some families have all girls, some all boys, and some are mixed, well, that is all about the sperm cell that survived the journey. Sperm cells will die quickly after being released by the male. They all don't have the exact same time of death, some die during the journey and cannot make it because of the woman's reproductive organs fluids, some die because they get stuck, some die because of their chromosome set. I want you to focus on the chromosome set, it is said that it has two sets of chromosomes the XX and XY but according to some studies, the XY Sperm Cell, the sperm cell that helps in the development of a male dies faster than the XX Sperm Cell which is slower than the XY but it lives longer. If a family has all girls then that means that the "slower but has a higher percentage of surviving" sperm cell managed to unite with the mature egg cell. If a family has all boys then that is somewhat to be lucky because the XY Sperm Cell managed to outrun its expiration date and unite with the mature egg cell, each XY Sperm Cell luckily survived. If a family has a mixed numbers of sons and daughters then that just means that both XX and XY sperm cell managed to survive and unite.
I'm not a biologist, I'm not a specialist but, I hope this helps in answering your question.