BackgroundAre individual differences in attachment security inborn or shaped by the social environment? In infancy and early childhood, the evidence points to a substantial role of the environment, but a large twin study in early adolescence showed considerable heritability. Here we examined the twin heritability of attachment in middle childhood. We hypothesized that in middle childhood some heritability would emerge. Furthermore, we expected a role for cognitive and language abilities in explaining variance in attachment in middle childhood, partly related to the measurement of attachment, and we therefore examined associations with IQ.MethodsThis pre‐registered study included 415 same‐sex twin pairs (52% girls, 58% monozygotic) between 8 and 11 years old (M = 9.59, SD = 0.79). Participants were recruited from an experimental cohort‐sequential study including two age‐overlapping longitudinal cohorts. Secure Base Script Knowledge was assessed with the Middle Childhood Attachment Script Assessment . Zygosity of the twins was determined using DNA samples. In the younger cohort, cognitive development was assessed with the Dutch version of the Wechsler Preschool and Primary Scale of Intelligence . In the older cohort, the Dutch version of the Wechsler Intelligence Scale for Children was used .ResultsSignificant additive heritability (38%) was found in the absence of a common environment component. This result diverges from findings in infancy and early childhood and aligns with the results in early adolescence.ConclusionsThe gene–environment correlation hypothesis suggesting that older children more actively shape their experiences in social contexts may offer a plausible explanation for the heritability of attachment in middle childhood. In middle childhood this mechanism might tip the balance toward a larger role for additive genetics. Larger longitudinal twin studies are needed to replicate the heritability of attachment after preschool age.

中文翻译：

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儿童中期安全基础脚本知识的遗传性：一项带有依恋脚本评估的双胞胎研究


背景依恋安全感的个体差异是天生的还是受社会环境影响的？在婴儿期和儿童早期，证据表明环境起着重要作用，但青春期早期的一项大型双胞胎研究表明了相当大的遗传性。在这里，我们研究了童年中期依恋的双胞胎遗传性。我们假设在童年中期会出现一些遗传性。此外，我们预计认知和语言能力在解释童年中期依恋的差异方面发挥作用，部分与依恋的测量有关，因此我们研究了与智商的关联。方法这项预先注册的研究包括 415 对 8 至 11 岁的同性双胞胎 （52% 女孩，58% 同卵） （M = 9.59，SD = 0.79）。参与者是从一项实验队列序列研究中招募的，其中包括两个年龄重叠的纵向队列。安全的基本脚本知识通过中期儿童依恋脚本评估进行评估。使用 DNA 样本确定双胞胎的合度。在较年轻的队列中，使用荷兰版的韦氏学前班和初级智力量表评估认知发展。在较老的队列中，使用了荷兰版的韦氏儿童智力量表。结果在没有共同环境成分的情况下发现了显著的加性遗传力 （38%）。这一结果与婴儿期和儿童早期的发现不同，与青春期早期的结果一致。结论基因-环境相关假说表明，年龄较大的儿童在社会环境中更积极地塑造他们的经历，这可能为童年中期依恋的遗传性提供了一个合理的解释。 在童年中期，这种机制可能会使天平向加性遗传学发挥更大的作用倾斜。需要更大规模的纵向双胞胎研究来复制学龄前后依恋的遗传性。