Verweij Renske M, Mills Melinda C, Tropf Felix C, Veenstra René, Nyman Anastasia, Snieder Harold
Department of Sociology and ICS, University of Groningen, Groningen, The Netherlands.
Department of Sociology and Nuffield College, University of Oxford, Oxford, UK.
Eur J Hum Genet. 2017 Sep;25(9):1067-1074. doi: 10.1038/ejhg.2017.105. Epub 2017 Jul 5.
Previous research has found a genetic component of human reproduction and childlessness. Others have argued that the heritability of reproduction is counterintuitive due to a frequent misinterpretation that additive genetic variance in reproductive fitness should be close to zero. Yet it is plausible that different genetic loci operate in male and female fertility in the form of sexual dimorphism and that these genes are passed on to the next generation. This study examines the extent to which genetic factors influence childlessness and provides an empirical test of genetic sexual dimorphism. Data from the Swedish Twin Register (N=9942) is used to estimate a classical twin model, a genomic-relatedness-matrix restricted maximum likelihood (GREML) model on twins and estimates polygenic scores of age at first birth on childlessness. Results show that the variation in individual differences in childlessness is explained by genetic differences for 47% in the twin model and 59% for women and 56% for men using the GREML model. Using a polygenic score (PGS) of age at first birth (AFB), the odds of remaining childless are around 1.25 higher for individuals with 1 SD higher score on the AFB PGS, but only for women. We find that different sets of genes influence childlessness in men and in women. These findings provide insight into why people remain childless and give evidence of genetic sexual dimorphism.
先前的研究发现了人类生殖和无子女现象中的遗传因素。其他人则认为，生殖的遗传性之所以违反直觉，是因为人们经常误解生殖适应性中的加性遗传方差应该接近于零。然而，不同的基因座以性别二态性的形式在男性和女性生育能力中发挥作用，并且这些基因会传递给下一代，这是合理的。本研究考察了遗传因素对无子女现象的影响程度，并对遗传性别二态性进行了实证检验。利用瑞典双胞胎登记处的数据（N = 9942）来估计一个经典双胞胎模型、一个关于双胞胎的基因组相关性矩阵限制最大似然（GREML）模型，并估计首次生育年龄的多基因分数对无子女现象的影响。结果表明，在双胞胎模型中，无子女现象个体差异的变异有47%由遗传差异解释；在GREML模型中，女性为59%，男性为56%。使用首次生育年龄（AFB）的多基因分数（PGS），AFB PGS得分每高出1个标准差的个体，无子女的几率高出约1.25倍，但仅适用于女性。我们发现，不同的基因组合影响男性和女性的无子女现象。这些发现有助于深入了解人们无子女的原因，并为遗传性别二态性提供了证据。
