Re:How about children with two native languages? (Score 1)

This all makes sense, doesn't it?

If an infant grows up in a one-language house, concepts have a single name and there's no need to map more than one word for a single concept.

The cat is the cat is the cat.

There's never another word for it (besides "Morris" but this falls in line with the logic "the boy's name is "Tom" and he can be both Tom and a boy").

In a multilingual house, the cat is the cat, le chat and/or el gato, and the infant learns the flexibility to map more than a single language to any given object.

Once you've made that cognitive leap for the first language, the successive leaps are easier and easier... is just a matter of learning the words, not the concept that there can be other words for the same concept.