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IQ and Heredity

A little boy went up to his father and asked: "Dad, where did all of my intelligence come from?"

The father replied. "Well son, you must have got it from your mother, because I still have mine."

Well the above joke is certainly true by all means! IQ is largely depended on Heredity and it is one of the main factors among the other factors which determine differences in IQ. [Note] Intelligence quotient: a measure of a person's intelligence as indicated by an intelligence test.

Here I will discuss about the different ways Heredity influences one's IQ.

  1. Monozygotic/Identical Twins: - Occurs when a single egg is fertilized to form one zygote which then divides into two separate embryos. There is no significant difference in the IQ of the identical twins. This is because the twins are sharing identical genes.
  2. Dizygotic/Fraternal Twins: - Usually occurs when two fertilized eggs are implanted in the uterine wall at the same time. Such twins do not share the same IQ level because they share roughly about 50% of the genes.
  3. Familial Relationships: - It has been found that the IQ among the first-degree relative is almost similar. For example brother-sister and parent-children will share almost same level of IQ. Genes play a vital part in determining one's IQ.
  4. Adoption: - Adoption has no role to play in regards to the IQ of the adopted children. Adopted children will have the genes of their biological parents and so the IQ which they will resemble will be that of their biological parents and not of their adoptive parents.
  5. Inbreeding Depression:-Inbreeding is very uncommon in our society however some cases of inbreeding have been reported. Children whose parents are first-cousins or second-cousins have a lower IQ than the children whose parents are not related at all.
  6. Heterosis: - Heterosis is the opposite of inbreeding depression. As a result of Heterosis the offspring is blessed with a good IQ level as compared to the IQ of the offspring whose parents comes from the same stock.
  7. Environmental Factors : - Environmental factors play a role in determining IQ. Proper childhood nutrition is critical for cognitive development; malnutrition can lower IQ.

Genetic Factors are very important in determining one's IQ and I hope I have justified it!

Scientists are still figuring out other possibilities which might be responsible for one's IQ. However whatever they come up with, Genetic factors will anyway still be the main factor determining one's IQ.

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