A.H. Sinclair, P. Berta, M.S. Palmer, J.R. Hawkins, et al., "A gene from the human sex-determining region encodes a protein with homology to a conserved DNA-binding motif," Nature, 346:240-44, 1990 Andrew Sinclair (Human Molecular Genetics Laboratory, Imperial Cancer Research Fund, London):
"Throughout history people have wondered what determines the sex of an individual. In short, how do you get a boy or girl?
"Several theories were proposed by the ancient Greeks: Democritus believed the uterus determined sex, depending on the state of menstrual flow at conception and whether the embryo implanted on the left side or on the right side.
"Aristotle proposed that very old couples and very young couples would generally have girls because of the `degenerate' or `immature' state of their reproductive fluids.
"We now know that an embryo that inherits a Y chromosome develops as a male, whereas an embryo lacking a Y chromosome develops as a ...
