Confronting Friends and Family

[festive1]

That's entirely wrong. First of all, language is dependent on genes.

Then try teaching a language to a feral human.

The human brain has a function called the Language Acquisition Device. It allows for rapid language development, but there is a relatively brief window in early childhood where this is operable. If a child misses this window, they have a much more difficult time acquiring the ability to master language. A feral human would have missed this window. This is why it's recommended that you read to your kids. It's basic developmental psychology.