Environmental Factors of IQ:
Newmann, Freeman, and Holzinger from studies of twins concluded that social and educational environmental differences strongly affect intelligence despite genetic similarities. The monozygotic twins reared apart don’t achieve the same IQ level.
The environmental components influencing IQ performance are:
1. Size of the family: A number of studies have shown that the greater is the number of children in a family the lower the IQ per child.
2. Culture: IQ differences are found to exist between different races, between different religious groups, and between different regions of the world.
3. Early environment and mother: Intellectual and emotional retardation is found in children who are deprived of stimuli during early stages.
4. Dietary effects: Severe malnutrition of the embryo or infant affects most aspects of development and reduced intelligence.