Explain with reference to Mia and Gia
The evidence for hereditary influences on intelligence comes mainly from studies on twins and adopted children. The intelligence of identical twins reared together correlates almost 0.90. The intelligence of identical twins reared in different environments correlated 0.72.
Environmental deprivation lowers intelligence while rich nutrition, good family background, and quality schooling increases intelligence.
There is a general consensus among psychologists that intelligence is a product of complex interaction of heredity (nature) and environment (nurture).