Haji and Seb are identical twins who went to different adoptive families as infants. When they meet for a study at age 35, researchers find that Haji's measured IQ is 116 and Seb's is 97. Since they share the same genes and intelligence is highly heritable, how is this possible? Choose the best answer.
A) The brothers were probably given IQ tests by researchers who scored the tests differently.
B) IQ is not a valid indicator of ability, so people with similar intelligence often score very differently.
C) The environment affected where on the inherited reaction range each brother's IQ developed.
D) IQ is not controlled by genes even though intelligence is highly heritable.

Question

Quizplus · Accepted Answer

While intelligence is highly heritable, the environment can still play a large role in where on the inherited reaction range an individual's IQ develops. Factors such as diet, education, and access to resources can all impact IQ scores. Therefore, even identical twins raised in different environments can show variation in their measured IQ.

Haji and Seb Are Identical Twins Who Went to Different