Objective

Callous-unemotional (CU) traits increase risk for children to develop severe childhood aggression and conduct disorder. CU traits are typically described as highly heritable, and debate continues about whether the parenting environment matters in their etiology. Strong genetically informed designs are needed to test for the presence of environmental links between parenting practices and CU traits. Our objective was to determine whether parental harshness and parental warmth were related to children’s aggression or CU traits when accounting for genetically mediated effects.

Method

We examined 227 monozygotic twin pairs (454 children) drawn from population-based and at-risk samples of twin families, leading to oversampling of twins living in poverty. We computed multi-informant difference scores combining mother and father reports of their harshness and warmth toward each twin, and differences in mother reports of each twin’s aggression and CU traits.

Results

Twin differences in parental harshness were related to differences in both aggression and CU traits, such that the twin who received harsher parenting had higher aggression and more CU traits. Differences in parental warmth were uniquely related to differences in CU traits, such that the twin receiving warmer parenting evidenced lower CU traits. These effects were not moderated by child sex, age, or family income, with the exception that the relationship between differential parental harshness and differential child aggression was stronger among low-income families.

Conclusion

Parenting is related to child CU traits and aggression, over and above genetically mediated effects, with low parental warmth being a unique environmental correlate of CU traits.

中文翻译：

---

育儿是无情的性格和侵略的环境预测因子：单卵双胞胎差异研究。

客观的

残酷无情的（CU）性状增加了儿童发展严重的童年侵略和品行障碍的风险。CU的特征通常被描述为高度可遗传的，关于育儿环境是否在其病因中起重要作用的争论仍在继续。需要强有力的遗传学信息设计来测试育儿习惯和CU特性之间是否存在环境联系。我们的目的是确定在考虑遗传介导的影响时，父母的苛刻程度和父母的热情是否与儿童的攻击性或CU特征有关。

方法

我们检查了227个单卵双胞胎对（454名儿童），这些双胞胎是从以人口为基础的高危双胞胎样本中抽取的，导致了生活在贫困中的双胞胎的抽样过多。我们计算了多信息差异分数，结合了父母对每个双胞胎的苛刻程度和温暖程度的报告，以及母亲对每个双胞胎的侵略性和CU特征的报告的差异。

结果

父母严酷程度的双胞胎差异与侵略性和铜质性状的差异有关，因此，父母养育度更高的双胞胎具有较高的攻击性和更多的铜质性状。父母温暖的差异与铜质特征的差异是唯一相关的，因此，双胞胎接受较温和的父母养育表现出较低的铜质特征。这些影响并未因孩子的性别，年龄或家庭收入而减缓，除了在低收入家庭中，父母对父母的苛刻程度与儿童对孩子的攻击程度之间的关系更强。

结论

除了遗传介导的影响外，育儿还与儿童的铜质性状和侵略性有关，父母的低温暖是铜质性状的独特环境因素。