The Minnesota twin design compared 375 twin pairs both reared together and apart

Evidence

In December 1988 the anticipated article on genetic determinants of “ordinary” personality traits appeared in the Journal of Personality and Social Psychology (Tellegen et al., 1988), based on a design other researchers could only lust after. In the study 217 pairs of identical twins reared together had answered Tellegen’s Multidimensional Personality Questionnaire (MPQ) between 1970 and 1984, as had 114 pairs of fraternal twins raised together. Another 44 pairs of monozygotic twins reared apart, and 27 dizygotic twins reared apart, also completed this test between 1979 and 1986. — Bob Altemeyer, The Authoritarian Specter, 898

Categorization

• XREF: The twin design is the gold standard for partitioning genetic vs. environmental variance — central to behavioral genetics methodology.