Kanazawa Satoshi, Apari Péter
Department of Management, London School of Economics and Political Science, London, UK.
Ann Hum Biol. 2009 May-Jun;36(3):320-30. doi: 10.1080/03014460902766918.
The generalized Trivers-Willard hypothesis (gTWH) proposes that parents who possess any heritable trait which increases male reproductive success at a greater rate than female reproductive success in a given environment will 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 will have a lower-than-expected offspring sex ratio.
One heritable trait which increases the reproductive success of sons much more than that of daughters is unrestricted sociosexual orientation. We therefore predict that parents with unrestricted sociosexual orientation (measured by the number of sexual partners, frequency of sex, and attitudes toward relationship commitment and sexual exclusivity) have a higher-than-expected offspring sex ratio (more sons).
We analyse the US General Social Surveys and the National Longitudinal Study of Adolescent Health (Add Health), both with large nationally representative samples.
Our analyses support the prediction from the gTWH.
One standard deviation increase in unrestrictedness of sociosexual orientation increases the odds of having a son by 12-19% in the representative American samples.
广义特里弗斯-威拉德假说（gTWH）提出，在特定环境中，拥有任何可遗传性状且该性状提高男性生殖成功率的速度高于女性生殖成功率的父母，其后代性别比将高于预期；而在特定环境中，拥有任何可遗传性状且该性状提高女性生殖成功率的速度高于男性生殖成功率的父母，其后代性别比将低于预期。
一种可遗传性状——不受限制的社会性取向，相比女儿，它能极大地提高儿子的生殖成功率。因此，我们预测，具有不受限制的社会性取向（通过性伴侣数量、性行为频率以及对关系承诺和性排他性的态度来衡量）的父母，其后代性别比高于预期（儿子更多）。
我们分析了美国综合社会调查和青少年健康全国纵向研究（Add Health），这两项调查都有具有全国代表性的大样本。
我们的分析支持了gTWH的预测。
在美国代表性样本中，社会性取向不受限制程度每增加一个标准差，生儿子的几率就会增加12% - 19%。
