Genetic Influence Helps Explain Variation in Human Fertility Outcomes: Evidence from Recent Behavioral and Molecular Genetic Studies
Joseph L. Rodgers, Kimberly Hughes, Hans-Peter Kohler, Kaare Christensen, Debby Doughty, David C. Rowe and Warren B. Miller
Abstract: To search for genetic influences on human fertility appears inconsistent with past empirical research and prior interpretations of Fisher's Fundamental Theorem of Natural Selection. We discuss Fisher's Theorem and give reasons why genetic influences may indeed account for individual differences in human fertility. We review recent empirical studies conducted by the authors showing genetic influence on variance in fertility outcomes, fertility precursors, and a genetic link between the two. Findings from different cultures, different times, different levels of data, and both behavioral and molecular genetic designs lead to the same conclusion: Fertility differentials are genetically influenced, and at least part of the influence derives from behavioral precursors that are under volitional control, which are themselves genetically mediated.