An introvert-prone child grows up in a very social home. She may become:

1. The child's genotype predisposes her to be introverted. 2. An environment that promotes social interaction and extroversion may make her a little extroverted. 3. Genes set the range, so she is unlikely to turn fully extroverted, but the environment still moves her within it. _Source: NCERT Class XI Psychology, Ch 3 Human Development, "FACTORS INFLUENCING DEVELOPMENT", p. 42_