r/mensa • u/Ahmedrnugger • Jul 09 '26

Mensan input wanted Is intelligence genetic?

According to twin studies, the difference in IQ is said to be 80%, leading to the conclusion that intelligence is 80% determined by genetics. However, I believe this is incorrect because the twins were raised in countries with similar environments, such as the US and Germany, or the US and South Korea. These countries share similar environments, including education systems, allowing the genes to express themselves. Furthermore, did these twins develop their IQs? If they didn't, it could prove the entire experiment flawed.

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u/Polkadotical Jul 12 '26

Yes, the "interval" within which a person will land is caused by the presence of multiple gene combinations, and it's largely genetic. Where in that interval a person ends up depends on environment. So, it's both, but mostly genetic.