1
Aim
to estimate heritability of IQ
2
Method
A meta-analysis of 111 studies on heritability of IQ that included monozygotic and dizygotic twins who were reared together and apart
3
Procedures
Researchers selected studies based on a number of criteria; cleaned the data, and calculated median correlations between IQ scores of individuals of interest (monozygotic and dizygotic twins)
4
Results
Monozygotic twins reared together: 85% IQ correlation
Monozygotic twins reared apart: 67% IQ correlation
Dizygotic twins reared together: 58% IQ correlation
Dizygotic twins reared apart: 45% IQ correlation
5
Conclusion
- The study demonstrates intelligence is inherited to a considerable extent
- But, it is not completely inherited... for monozygotic twins reared together, the correlation between their IQ scores is not perfect, which shows that environment also plays a role in IQ development