Introduction to All that Development and Language Practice Test

Genetic influence on temperament is being tested here. Identical twins share the same genes, so their similar temperaments point to heredity predisposing temperament. This pattern is a hallmark of a heritable trait: when twins show similar temperamental tendencies, it suggests genetic factors contribute to those traits. While environment matters, the observation specifically supports the idea that biology shapes temperament. The other options don’t fit because they refer to a particular temperament category or to an unrelated study, not to the genetic influence demonstrated by twin similarity.