At what age do children start to show a preference for people who are most similar to themselves?

Question

Quizplus · Accepted Answer

Research has shown that by as early as 9 months old, babies tend to show a preference for people who are most similar to themselves, such as people of the same race or language. This preference for similarity is thought to be tied to the development of social identity, which occurs in infancy and childhood.

At What Age Do Children Start to Show a Preference