Hur Y M, McGue M, Iacono W G
Department of Psychology, University of Minnesota, Minneapolis 55455, USA.
Behav Genet. 1995 Jul;25(4):337-40. doi: 10.1007/BF02197282.
It is generally believed that in Caucasian populations the rate of monozygotic (MZ) twinning is approximately equal to the rate of like-sex dizygotic (DZ) twinning so that representative samples of like-sex twins should contain approximately equal numbers of MZ and DZ twins. Recent evidence suggests, however, that the rate of DZ twinning in Caucasian populations has declined over the past 50 years so that there are now many more MZ than like-sex DZ twin births (Jeanneret and MacMahon, 1962; James, 1972; Mosteller et al., 1981; Doherty and Lancaster, 1986; Lykken et al., 1990). We report additional evidence of a higher rate of MZ than like-sex DZ twinning from Minnesota for the birth years 1971-1984. The convergence of evidence thus suggests that the observation of a greater number of MZ than DZ twins in a volunteer twin sample can no longer necessarily be taken as a sign of ascertainment bias.
一般认为，在白种人群体中，同卵双胞胎（MZ）的发生率大约等于同性异卵双胞胎（DZ）的发生率，因此，同性双胞胎的代表性样本应包含数量大致相等的MZ和DZ双胞胎。然而，最近有证据表明，在过去50年中，白种人群体中DZ双胞胎的发生率有所下降，因此现在出生的MZ双胞胎比同性DZ双胞胎多得多（让内雷和麦克马洪，1962年；詹姆斯，1972年；莫斯特勒等人，1981年；多尔蒂和兰卡斯特，1986年；莱肯等人，1990年）。我们报告了明尼苏达州1971年至1984年出生年份中MZ双胞胎发生率高于同性DZ双胞胎的更多证据。因此，证据的趋同表明，在志愿者双胞胎样本中观察到的MZ双胞胎数量多于DZ双胞胎，不再一定能被视为确定偏倚的迹象。
