https://en.m.wikipedia.org/wiki/Critical_period_hypothesis https://en.m.wikipedia.org/wiki/Critical_period_hypothesis There has been and continues to be a lot

https://en.m.wikipedia.org/wiki/Critical_period_hypothesis https://en.m.wikipedia.org/wiki/Critical_period_hypothesis There has been and continues to be a lot of research behind that cope. The effortless mastery over e..g. phonology that children emerge with is very difficult to replicate in adulthood, even after decades of speaking.