What factors determine the IQ of a person?

IQ is determined by many factors which include both genetic and non-genetic factors. Other modifiable environmental factors like education, premature birth, nutrition, drugs, alcohol abuse, pollution, mental illnesses, social structures, family and diseases also play a major role in determining IQ of an individual.

The evidence of genetic influences in IQ was demonstrated in the study of twins which showed that identical twins IQ’s are more similar than those of fraternal twins.

The evidence of environmental influence in IQ was demonstrated in the study of identical twins reared apart. It was discovered that the IQ of identical twins reared apart are less similar compared to those reared in the same environment.

IQ is determined by both genetic as well as non-genetic factors. Even though genetic factors play a role, various other environmental influences can make-up the IQ of an individual. The environment consists of a wide range of simulators that the person is surrounded. The variables involved include family, education, social structure, and peer groups. All of these have been linked to differences in IQ.

For example, studies have shown that first-born children tend to have higher IQ than later-born siblings. Many experts believe that this is because first-born children receive more attention from parents. Research also infers that parents tend to expect more from their older children, while later-born siblings experience a lesser degree of expectations. Breastfeeding, womb conditions, and nutrition also play a crucial role in IQ.