Department of Psychology/Elliott Hall, University of Minnesota, Minneapolis, MN 55455, USA.
Behav Genet. 2013 Jan;43(1):1-12. doi: 10.1007/s10519-012-9559-5. Epub 2012 Aug 28.
While a substantial amount of behavioral genetic research has helped to characterize developmental trends in twin similarity in early life, relatively little is known about changes in twin similarity with age in adulthood. We investigated age moderation of twin similarity for a composite measure of cognitive ability, depression symptomatology and hand grip strength in a cross-sectional sample of 2,332 like-sex pairs of Danish twins age 46-96 years. All three outcomes were strongly correlated with age, indicating that the three phenotypes analyzed are not developmentally static. Nonetheless, in moderated regression analysis we found no evidence of declining twin similarity for any of the three outcomes in either zygosity group. Moreover, biometric analysis of the twin data revealed minimal differences in heritability estimates across the age range sampled. While small sample size limits our ability to draw firm conclusions at very advanced ages, these findings call into question the hypothesis that the cumulative impact of life experiences diminishes twin similarity at least through age 80. We hypothesize that twins are able to maintain similarity over extended periods of time because in part they are able to construct similar environments that reinforce that similarity.
尽管大量行为遗传学研究有助于描述双胞胎在生命早期相似性的发展趋势，但对于成年人年龄变化对双胞胎相似性的影响却知之甚少。我们在丹麦双胞胎 46-96 岁的横截面样本中，调查了认知能力、抑郁症状和握力的综合衡量标准的双胞胎相似性的年龄调节作用。所有三个结果都与年龄密切相关，这表明分析的三种表型并非在发育上是静态的。尽管如此，在调节回归分析中，我们没有发现任何证据表明，在任何一种同卵双胞胎组中，这三个结果的双胞胎相似性会随着年龄的增长而下降。此外，对双胞胎数据的生物计量分析显示，在取样的年龄范围内，遗传率估计值差异极小。虽然样本量小限制了我们在非常高龄时得出确凿结论的能力，但这些发现对以下假设提出了质疑，即生活经历的累积影响至少在 80 岁之前会降低双胞胎的相似性。我们假设，双胞胎能够在很长一段时间内保持相似性，部分原因是他们能够构建相似的环境，强化这种相似性。
