An interaction between socioeconomic status (SES) and the heritability of IQ, such that the heritability of IQ increases with higher SES, has been reported in some US twin studies, although not in others, and has generally been absent in studies outside the US (England, Europe, Australia). Is such an interaction present in US adoption studies? Data from two such studies, the Texas and the Colorado Adoption Projects, were examined, involving 238–469 adopted children given IQ tests at various ages. A mini multi-level analysis was made of the prediction of the IQs by the SES of the rearing home (a composite of parental education and occupation), by the birth mother’s intelligence, and by the interaction of the two. Neither study showed any substantial heritability × SES interaction: the effect size estimates in units comparable to twin moderation models were negative (− 0.042 and − 0.004), and the meta-analytic estimate for the combined analysis was − 0.27 (SE = 0.042) with a 95% confidence interval of − 0.109 to 0.054. Thus, while we cannot rule out positive moderation based on our two studies, the joint agreement across these studies, and with the non-US twin studies, warrants attention in further research. SES may not fully capture proximal familial-environmental aspects that moderate child IQ.

一些美国双胞胎研究报道了社会经济地位 (SES) 与 IQ 遗传力之间的相互作用，即 IQ 的遗传力随着 SES 的增加而增加，但在其他研究中却没有，而且在美国以外的研究中普遍没有出现（英国、欧洲、澳大利亚）。美国收养中是否存在这种互动学习？对德克萨斯和科罗拉多收养项目这两项此类研究的数据进行了检查，涉及 238-469 名接受过不同年龄智商测试的收养儿童。对抚养家庭的 SES（父母教育和职业的综合）、生母的智力以及两者的相互作用对 IQ 的预测进行了迷你多层次分析。两项研究均未显示任何实质性遗传力 × SES 相互作用：与双调节模型相当的单位效应量估计值为负（− 0.042 和 − 0.004），联合分析的荟萃分析估计值为 − 0.27 ( SE = 0.042)，95% 置信区间为 − 0.109 至 0.054。因此，虽然我们不能排除基于我们的两项研究的积极调节，但这些研究之间的联合协议以及与非美国双胞胎研究的联合协议值得进一步研究关注。SES 可能无法完全捕捉到调节儿童智商的近端家庭环境方面。