> To master a first native language takes at least about 16 years for most people What's your definition of master? That doesn't sound like the kids I'm thinki

> To master a first native language takes at least about 16 years for most people What's your definition of master? That doesn't sound like the kids I'm thinking of when I think 'learnt English' and mastering a second language to the same level of mastery as the first I am unsure can be done in a shorter timespan (though conversational fluency to the point where one can understand and be understood is on a significantly shorter time-scale.)