Studies of Reared-Apart (Separated) Twins: Facts and Fallacies

von freakoutcrazy

Twin studies supply the most frequently cited evidence in favor of important genetic influences on human behavioral differences. Examples of human behavior include IQ, personality, socially disapproved behavior such as criminality, political behavior and ideology, and psychiatric disorders. Almost all twin studies are based on classical twin method comparisons between MZ (monozygotic, identical) and DZ (dizygotic, fraternal) twin pairs reared together in the same family home. MZ pairs are said to share 100% of their segregating genes, whereas (like ordinary siblings) DZ pairs are said to share only 50% on average.1