Intellectual development is the product of a complex interplay of hereditary factor (nature) and environmental conditions (nurture). Heredity sets the range and environment shapes the development.
Nature (Hereditary factors): The most convincing evidence comes from twin studies and adoption studies. influences intelligence.
| Studies |
Correlation |
| Identical twins reared together |
0.90 |
| Identical twins reared in different environments |
0.72 |
| Fraternal twins reared together |
0.60 |
| Siblings reared together |
0.50 |
| Siblings reared apart |
0.25 |
Nurture (Environmental factors): Evidence for environmental influences on intelligence comes from the following observations: Adoption studies demonstrate that adopted children show some similarity in IQ to their adoptive parents.IQ declines over time in children raised in deprived environments. Conversely, IQ improves in children who leave deprived environments and enter enriched environments. Family background and socio-economic status; Nutrition; Schooling etc.
