Contemporary Research
In what is perhaps the most famous twin study, the Minnesota Study of Twins Reared Apart (MISTRA), Bouchard, Lykken, McGue, Segal, and Tellegen (1990) studied more than 80 sets of MZ and DZ twins who were separated as infants and raised in separate environments in order to determine the heritability of psychological traits, including intelligence. The participants completed approximately 50 hours of assessment, including personality and occupational interest inventories, mental ability batteries, an IQ test, and interviews about life history (Bouchard et al. 1990, p. 223). Systematic assessments of the environments in which the twins were raised were also performed (Bouchard et al., 1990, p. 223).
In analyzing the data …show more content…
The Texas Adoption Project started with 300 families who had adopted a child, many of whom were successfully followed up multiple times over 35 years with assessments for parents and children, and added assessments mailed to 220 families who had completed earlier adoptions (Loehlin & Horn, 2012, p. 657). In analyzing the response data from the Minnesota Multiphasic Personality Inventory (MMPI) and Cattell’s Sixteen Personality Factor Questionnaire (16PF) for the original 300 families, plus the California Psychological Inventory (CPI) and the Thurstone Temperament Schedule (TTS) for the 220 families who had adopted earlier, Loehlin and Horn (2012) found that GFP correlations for genetically related family members was only slightly higher than GFP correlations for family members without shared DNA and that the greatest factor in GFP seems to be individual (p. 661). The authors also noted that in adoption studies of biologically related individuals, the correlations are often not as strong as in twin studies of MZ pairs (p. …show more content…
490). The meta-analysis found evidence of genotype-environment interaction and both shared and nonshared environmental influences, such as exposure to parenting style and peer selection, contributing to antisocial behavior (pp. 520-521) When these results are contrasted with the 70% variance that Bouchard (1990) attributed to genetic influence on IQ, it seems likely that aptitude and ability are influenced very highly by genetic traits and that personality and character traits are influenced by a combination or interaction of genotype and environmental
In what is perhaps the most famous twin study, the Minnesota Study of Twins Reared Apart (MISTRA), Bouchard, Lykken, McGue, Segal, and Tellegen (1990) studied more than 80 sets of MZ and DZ twins who were separated as infants and raised in separate environments in order to determine the heritability of psychological traits, including intelligence. The participants completed approximately 50 hours of assessment, including personality and occupational interest inventories, mental ability batteries, an IQ test, and interviews about life history (Bouchard et al. 1990, p. 223). Systematic assessments of the environments in which the twins were raised were also performed (Bouchard et al., 1990, p. 223).
In analyzing the data …show more content…
The Texas Adoption Project started with 300 families who had adopted a child, many of whom were successfully followed up multiple times over 35 years with assessments for parents and children, and added assessments mailed to 220 families who had completed earlier adoptions (Loehlin & Horn, 2012, p. 657). In analyzing the response data from the Minnesota Multiphasic Personality Inventory (MMPI) and Cattell’s Sixteen Personality Factor Questionnaire (16PF) for the original 300 families, plus the California Psychological Inventory (CPI) and the Thurstone Temperament Schedule (TTS) for the 220 families who had adopted earlier, Loehlin and Horn (2012) found that GFP correlations for genetically related family members was only slightly higher than GFP correlations for family members without shared DNA and that the greatest factor in GFP seems to be individual (p. 661). The authors also noted that in adoption studies of biologically related individuals, the correlations are often not as strong as in twin studies of MZ pairs (p. …show more content…
490). The meta-analysis found evidence of genotype-environment interaction and both shared and nonshared environmental influences, such as exposure to parenting style and peer selection, contributing to antisocial behavior (pp. 520-521) When these results are contrasted with the 70% variance that Bouchard (1990) attributed to genetic influence on IQ, it seems likely that aptitude and ability are influenced very highly by genetic traits and that personality and character traits are influenced by a combination or interaction of genotype and environmental