Analyses of twin mortality often use models with dependent unobserved frailty terms capturing genetic and childhood environmental determinants. This ignores that mortality rates can be co-dependent due to bereavement effects, that is, to a causal effect of the loss of the co-twin on the mortality rate of the surviving twin. We develop a novel approach based on a model incorporating both types of dependence. We prove identification and we estimate models with Danish register data on twin pairs. Among men, losing an identical co-twin at age 75 causally reduces the remaining lifetime on average by more than a year. This bereavement effect is less severe among non-identical twins. The results are relevant for the assessment of the economic component of bereavement effects in general. Furthermore, estimates of correlations between the frailty terms by zygosity and the ensuing relative importance of genetic determinants are highly dependent on whether bereavement effects are ignored.

中文翻译：

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独特的纽带：双胞胎丧亲和同卵双胞胎的寿命关联

对双胞胎死亡率的分析通常使用具有相关未观察到的脆弱术语的模型，这些术语捕捉遗传和儿童环境决定因素。这忽略了死亡率可能因丧亲效应而相互依赖，即失去同胞双胞胎对幸存双胞胎死亡率的因果影响。我们开发了一种基于包含两种依赖类型的模型的新方法。我们证明了身份，并且我们估计了具有丹麦注册数据的双胞胎模型。在男性中，在 75 岁时失去同卵双胞胎会使剩余寿命平均减少一年多。这种丧亲效应在异卵双胞胎中不太严重。结果与评估丧亲效应的经济成分有关。此外，