Wexler assumes a normal distribution of human IQ, with an average of 100 and a standard deviation of 15. So as long as we can calculate the difference in standard deviation between the average of a person and his group, we can get his IQ.
Influencing factors of IQ
First, heredity: Generally speaking, the IQ of parents is high, and the IQ of children will not be low. This genetic factor is also manifested in blood relationship. Parents are local, and the average IQ of children is 102. The IQ of children born of parents married in different provinces is109; Parents are cousins, and the number of children with low IQ has increased significantly.
Second, breast milk: breast milk contains a variety of active substances that promote children's intellectual development, especially taurine, which has an important impact on intellectual development, which is 10 times higher than milk. According to the survey, the IQ of children who grow up with breast milk is about 3~ 10 higher than that of children who grow up with milk substitutes.
Third, diet: monotonous diet leads to the lack of some trace elements, or too little diet, protein and other serious nutritional deficiencies will lead to IQ retardation. Excessive intake of heavy metals such as lead and copper will also affect IQ.
Refer to the above? Baidu encyclopedia-IQ