Wang Siwen, Rosner Bernard A, Huang Hongyan, Rich-Edwards Janet W, Laden Francine, Hart Jaime E, Penney Kathryn L, Chavarro Jorge E
Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Sci Adv. 2025 Jul 18;11(29):eadu7402. doi: 10.1126/sciadv.adu7402.
Some families consistently have offspring of only one sex, raising questions about whether sex at birth is truly random. This study investigated whether offspring sex follows a simple binomial distribution within families and identified maternal factors associated with unisexual sibships. We analyzed 58,007 US women with two or more singleton live births (146,064 pregnancies, 1956-2015). Offspring sex followed a beta-binomial rather than a simple binomial distribution, indicating that each family may have a unique probability of male or female births, akin to a weighted coin toss. Deviations from simple binomial distribution were more pronounced when we excluded each woman's last birth to reduce the influence of sex-based stopping behavior. After excluding the last birth, older maternal age at first birth was associated with higher odds of having offspring of only one sex. A genome-wide association study identified maternal SNPs linked to having female-only () and male-only () offspring. Our findings suggest maternal factors influence offspring sex distributions.
一些家庭总是生育单一性别的后代，这引发了关于出生时的性别是否真的是随机的疑问。本研究调查了家庭内后代性别是否遵循简单的二项分布，并确定了与单性别同胞关系相关的母体因素。我们分析了58007名有两次或更多次单胎活产（146064次妊娠，1956 - 2015年）的美国女性。后代性别遵循贝塔二项分布而非简单的二项分布，这表明每个家庭生男或生女可能有独特的概率，类似于加权抛硬币。当我们排除每位女性的最后一次生育以减少基于性别的生育停止行为的影响时，与简单二项分布的偏差更为明显。排除最后一次生育后，首次生育时母亲年龄较大与生育单一性别的后代的几率较高有关。一项全基因组关联研究确定了与只生育女性（）和只生育男性（）后代相关的母体单核苷酸多态性。我们的研究结果表明母体因素会影响后代的性别分布。
