Even identical twin studies (which have inherent problems with them) suggest that a large percentage of IQ is determined by the environment.
Yes, this is a correct statement. The design of studies to determine a numerical figure for the pre-Mendelian concept of "heritability" can only show a MINIMUM influence of environment, and the minimum influence of environment on IQ is fairly large. Most heritability studies are, by their nature, naturalistic rather than experimental studies and prove nothing about what degree of malleability (a separate issue anyway) might be found if an experimenter tried targeted environmental interventions. And, yes, there are monozygotic twins who are discordant for IQ, so there must be influences other than genes on IQ.
Yes, this is a correct statement. The design of studies to determine a numerical figure for the pre-Mendelian concept of "heritability" can only show a MINIMUM influence of environment, and the minimum influence of environment on IQ is fairly large. Most heritability studies are, by their nature, naturalistic rather than experimental studies and prove nothing about what degree of malleability (a separate issue anyway) might be found if an experimenter tried targeted environmental interventions. And, yes, there are monozygotic twins who are discordant for IQ, so there must be influences other than genes on IQ.