Name: Allison K Mocko
Is it true that when undergoing artificial insemination there is
a greater chance of conceiving a boy? Why?
I believe so. Normally the semen is centrifuged and the top
fraction picked off for insemination. Sperm swim up by instinct,
naturally, and so those that make it to the top in the artificially high
gravity are the fittest of the bunch, to be preferred for insemination
success. They also happen more often to be sperm carrying Y sex
chromosomes. The Y chromosome is half the size of the X chromosome, so
the sperm carrying it are lighter and tend to be able to swim faster.
The same effect may operate in the natural process: the percentage of
newborns that are boys is slightly higher than 50. The imbalance is
corrected by the higher death rate of baby boys.
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Update: June 2012