Presumably it’s this study: https://www.researchgate.net/profile/Elissa_Cameron/publication/23785727_A_Trivers-Willard_Effect_in_Contemporary_Humans_Male-Biased

Presumably it’s this study: https://www.researchgate.net/profile/Elissa_Cameron/publication/23785727_A_Trivers-Willard_Effect_in_Contemporary_Humans_Male-Biased_Sex_Ratios_among_Billionaires/links/0c96051ae6431a79d0000000/A-Trivers-Willard-Effect-in-Contemporary-Humans-Male-Biased-Sex-Ratios-among-Billionaires.pdf?origin=publication_detail https://www.researchgate.net/profile/Elissa_Cameron/publicat... It cited 60% male to female billionaire ratio on n of 350. But, the methodology was to use google and Wikipedia for research so a more honest claim might be “male offspring of billionaires show up in search results more often.” I suppose that factoid wouldn’t have been paid for by the publisher though.