FIRST LANGUAGE ACQUISITION

How did you come to speak your mother tongue? Our parents did not teach us how to walk and they did not teach us how to talk. However we learned from them. How can this be?

First, children begin speaking by trying to repeat what they haver heard their parents say. For example:
1. Daddy go
2. He hitted me!
3. No eat cake

Second, research shows that  while mothers often respond to the semantic content of what their children say (´No, that´s not a doggie, it´s a cow´), they very rarely respond to the grammatical status of  their children´s phrases. Indeed, when parents do respond to speech errors, they most often do it positively.
Over the years from 2-7, when language is mastered, children constantly adjust their grammar until it matches that of the  adult speaker population.
This critical period between the ages of 2-7 suggests that (first) language learning, like walking, is an innate capacity of human beings.