Monozygotic twins reared apart appear to be similar not just in looks but also in psychology and personality despite growing up apart, according to the study conducted by Bouchard and Lykken. A group of monozygotic reared apart twins underwent a week of intensive psychological and physiological tests including personality trait scales, attitude and occupational interest inventories, and intelligence tests. To assess the similarity of their family resources, participants were asked to fill out checklists of household belongings. Finally they were subjected to life history, psychiatric, and sexual history interviews. Their results were then compared to monozygotic twins reared together.
If environment is responsible for individual differences,
If environment is responsible for individual differences,