[tsimionescu]

Sure, but there are two caveats:

1. Kids take about 7-10 years of constant immersion to become fluent in a language

2. Child brains are different from adult brains, and it is likely that the ability to pick up a language in this way degrades significantly after a certain age

I'm not saying it is impossible to pick up a language without being told the grammar rules, just that it's much faster if you do learn them.

[cyphar]

> 2. Child brains are different from adult brains, and it is likely that the ability to pick up a language in this way degrades significantly after a certain age.

There is plenty of evidence which counters the latter part of this claim (see Stephen Krashen and the input hypothesis).