How do you think the language models children are exposed to
early in life impact their use of grammar?

I believe the language models children are exposed to at an early age greatly impacts the child's use of grammar. If things keep going as they are now, in a few years our language will be nothing as it is now. The new generations of humans keep evolving our language to make it more practical and lazy that who knows how grammar will be.  

Explanation:

because when you are around someone especially as a child, someone you live with or are with all the time soon has an impact on you and your learning you soon begin to have the erg to be like them and do as they do

Hope this helps you

Good luck!!!