Lykken D T, McGue M, Bouchard T J, Tellegen A
Department of Psychology, University of Minnesota, Minneapolis 55455.
Behav Genet. 1990 Sep;20(5):547-61. doi: 10.1007/BF01065871.
Evidence from the Finnish Twin Registry (e.g., Rose et al., 1988) shows that adult monozygotic (MZ) twins are more similar, within pairs, in personality if the cotwins are presently cohabiting or in frequent contact than if they are seldom in contact. Results of a follow-up study led Kaprio et al. (1990) to conclude that "changes in social contact between monozygotic cotwins precede (and causally contribute to) changes in their intrapair similarity" (p. 9). If true, this conclusion has important theoretical implications, e.g., many heritability estimates would have to be revised downward. We adduce evidence suggesting that similarity leads to contact, rather than the other way around. Low correlations between twins' frequency of contact and their absolute within-pair difference on all traits thus far studied indicates that, whichever the direction of causality, the relationship between MZ within-pair similarity and their frequency of contact is very weak.
来自芬兰双胞胎登记处的证据（例如，罗斯等人，1988年）表明，成年同卵双胞胎在性格方面，如果双胞胎目前同居或经常接触，那么他们在性格上比很少接触时更加相似。卡普里奥等人（1990年）的一项后续研究结果得出结论：“同卵双胞胎之间社会接触的变化先于（并因果性地导致）他们配对内相似性的变化”（第9页）。如果这是真的，这个结论具有重要的理论意义，例如，许多遗传率估计值将不得不向下修正。我们提出证据表明是相似性导致接触，而不是相反。双胞胎接触频率与他们在所研究的所有特征上的绝对配对内差异之间的低相关性表明，无论因果关系的方向如何，同卵双胞胎配对内相似性与其接触频率之间的关系非常微弱。
