the magnitude of a study's heritability estimate depends on the amount og genetic and environment variation from which it was calculate, and it cannot be applied to other kinds of situations. For example, in the minnesota study, there was relatively little environmental variation. all subjects were raised in industrialized contries ( Great Britain, Canada, and the United State) by parents who could meet the strict standard s required for adoption. acordingly, most of variation in the subject 's intelligence and personality resulted from genetic variation. if the twins had been separately adopted by European royrap stars. London adverting executives, and Argentinian army officers, the resulting heritability estimates for IG and personality would likely have been lower. Bouchard and his colleagues emphasize this point in their papers.
a commonly overlooked point about the role of genetic factors in the development of humant psychological difference by influencing experience. at first, this statement seem paradoxical