In the environment of evolutionary adaptedness language acquisition would not primarily occur in a nuclear family, children would spend a lot of time around not just their immediate family but also with other nursing mothers and children close in age and as they get older with children close on age more generally. They pick up pronunciation from the environment and all the other elements of a language too. This is why children will reject a language spoken only by one person in their environment starting around age three[1] and how you get distinct school/social class accents, like international school English or public school English in the U.K.
[1]http://www.todayifoundout.com/index.php/2012/08/a-man-once-t...
This guy spoke only Klingon to his son for the first three years of his life. The same rejection occurs with natural languages if only one person speaks it to a child so if you want your child to grow up bilingual they better hear your language from other people too.
Interesting, I've some previous and am currently in a situation where I actively correct a child learner, and they respond well to that correction wrt language, less so in behavioural aspects unfortunately ;o)
For clarity, what I do with mispronunciations is break down the word in to phonemes. Yellow is a classic, that a lot of kids struggle with, current child subject has a propensity to say "lellow", though he gets it right more often than not now (age 3) -- I break that down as "yuh-ell-oh" and have him say other words that he can pronounce like "yes" and "yum". So I go "yes, yes, yes, yes, yellow" whilst he listens, then we do it together.
Most early language acquisition is done at home, and for us that has meant away from other parents so I'm not really sure how others do it. I have seen the "aw that's cute" reaction to mispronunciation in the wild, which I guess is a blocker for some.