Science: It's A Boy, and Here's Why

Researchers pinpoint a gene that may determine sex

Ever since the time of Aristotle, scientists have been puzzled by exactly what determines whether a baby is a boy or a girl. Last week the ancient mystery appeared to have been unlocked. A nine-member team led by a geneticist at the Whitehead Institute for Biomedical Research in Cambridge, Mass., announced that an infant's sex seems to be fixed by a single gene called testis determining factor, or TDF. The discovery, declared Whitehead's director, Nobel Laureate David Baltimore, was the result of a "landmark set of experiments."

In the seventh week of embryonic growth, reported Chief Researcher David Page, the presence...

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