(ELI5) when babies are raised with bilingual families, are they learning it as just one jumbled language, or as two separate languages?

Question

Also would it become difficult to discern and seperate them when they join school for example, and interact with people that only speak one

In: 37

Answer 1

They will speak two languages, however, the fluency in each language usually will be different. Only a very small number of kids can speak two languages at true “native” level. One language tend to be worst than another, that even though they have perfect grammar and vocabulary, their accent do have quirks that you don’t see in people who only speak one language. Here are two outcomes that I always see:

A: Perfect accent when speak the school official language, heavy accent speak the parent language

B: Perfect accent when speak parent language, slight accent when speak school official language.

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I also see kid who move to another country at 4 years old, pick up perfect accent of this second language, but their native language stuck at a 4 years old level.