How many gay men owe their sexual orientation to fraternal birth order?
How many gay men owe their sexual orientation to fraternal birth order?
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DOI：
10.1023/a:1014031201935
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发表时间：
2002-02-01
影响因子：
3.8
通讯作者：
Bogaert, AF
中科院分区：
文献类型：
--
作者：
Cantor, JM;Blanchard, R;Bogaert, AF
在男性中，性取向与哥哥的数量有关，每增加一个哥哥，同性恋的几率就会增加大约33%。然而，这种现象，即兄弟出生顺序效应，只解释了一部分男同性恋者的性取向。为了估计这一比例的大小，我们推导了两种流行病学统计数据的广义形式：归因分数和人口归因分数，它们量化了一种疾病与可能导致这种疾病的物质的先前暴露之间的关系。在其常见形式中，这些统计数据只能计算两种暴露水平：暴露与未暴露。我们开发了一种适用于多重暴露的方法，在这种情况下，是哥哥的数量。这种非迭代方法需要从先前的逻辑回归分析中获得优势比，然后将其应用于当代男同性恋者的大量样本。结果显示，大约七分之一的男同性恋者将其性取向归因于兄弟出生顺序效应。他们还表明，在有3个或更多哥哥的男同性恋群体中，兄弟出生顺序的影响会超过所有其他导致同性恋的原因，而在有2.5个哥哥的理论群体中，兄弟出生顺序的影响恰好与所有其他导致同性恋的原因相等。对同性恋兄弟姐妹连锁识别同性恋基因位点的方法提出了建议。
In men, sexual orientation correlates with the number of older brothers, each additional older brother increasing the odds of homosexuality by approximately 33%. However, this phenomenon, the fraternal birth order effect, accounts for the sexual orientation of only a proportion of gay men. To estimate the size of this proportion, we derived generalized forms of two epidemiological statistics the attributable fraction and the population attributable fraction, which quantify the relationship between a condition and prior exposure to an agent that can cause it. In their common forms, these statistics are calculable only for 2 levels of exposure: exposed versus not-exposed. We developed a method applicable to agents with multiple levels of exposure-in this case, number of older brothers. This noniterative method, which requires the odds ratio from a prior logistic regression analysis, was then applied to a large contemporary sample of gay men. The results showed that roughly 1 gay man in 7 owes his sexual orientation to the fraternal birth order effect. They also showed that the effect of fraternal birth order would exceed all other causes of homosexuality in groups of gay men with 3 or more older brothers and would precisely equal all other causes in a theoretical group with 2.5 older brothers. Implications are suggested for the gay sib-pair linkage method of identifying genetic loci for homosexuality.