Do violent men have more sons?
The generalized Trivers–Willard hypothesis (gTWH) [Kanazawa, S., 2005a. Big and tall parents have more sons; further generalizations of the Trivers–Willard hypothesis. J. Theor. Biol. 235, 583–590] proposes that parents who possess any heritable trait which increases the male reproductive success at a greater rate than female reproductive success in a given environment have a higher-than-expected offspring sex ratio, and parents who possess any heritable trait which increases the female reproductive success at a greater rate than male reproductive success in a given environment have a lower-than-expected offspring sex ratio. One heritable trait which increases the reproductive success of sons significantly more than that of daughters in the ancestral environment is the tendency toward violence and aggression. I therefore predict that violent parents have a higher-than-expected offspring sex ratio (more sons). The analysis of both American samples and a British sample demonstrates that battered women, who are mated to violent men, have significantly more sons than daughters.
Source: “Violent men have more sons: Further evidence for the generalized Trivers–Willard hypothesis (gTWH)” from Journal of Theoretical Biology, Volume 239, Issue 4, 21 April 2006, Pages 450-459
Kanazawa’s book is: Why Beautiful People Have More Daughters: From Dating, Shopping, and Praying to Going to War and Becoming a Billionaire– Two Evolutionary Psychologists Explain Why We Do What We Do.
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