Evidence for Sex Ratio Adjustment in Humans

It’s a Boy! Evidence for Sex Ratio Adjustment in Humans. Kristen J. Navara. Chapter in Choosing Sexes pp 13-31. https://link.springer.com/chapter/10.1007/978-3-319-71271-0_2

Abstract: Since the beginning of human existence, there has been a keen interest in the factors that influence whether a boy or girl is produced and the development of practices or methods to control it. While the overall natal ratio of boys to girls produced by humans hovers at a stable 1.06 boys for every girl, there is now evidence that these sex ratios vary substantially among populations, in response to severe life events, in conjunction with the position and timing of intercourse, and even with ambient temperature. In this chapter, I compile the evidence implicating many of these factors as modulators of offspring sex ratios in humans and discuss how these influences may interact to determine whether a boy or a girl is produced.