JAMA. 1943;121(5):348. doi:10.1001/jama.1943.02840050046015.
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From earliest antiquity scientists, philosophers and magicians have speculated as to why the offspring is male or female. Biologists have attempted to discover means by which the desired sex could be produced at will. Only with the advent of this century, however, has any scientific foundation for this eventuality been developed. Among the most important early observations was the demonstration that sex among higher animals is determined by genes. Thereafter it became clear that sex is determined in human beings (as in some lower animals) at the time of the fertilization of the egg. Subsequent activity, whether dietary or metabolic, does not change the sex of the child. Furthermore, to the astonishment and possibly distress of some of those with preconceived ideas, human sex is determined by the presence or absence of a particular gene or set of genes of the father rather than by the mother. No longer may


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