This gives us some idea of what exactly constitutes our linguistic knowledge. Whatever it is, it's universal -it is acquired regardless of culture, language, class, etc.
Child acquires language.
Not late at all, above average, in fact. Turns out that the reason blind children are on the average 6 months later than sighted children in acquiring language is that the vast majority of blind children at that time were blinded immediately following birth by oxygen administered because they were on the average 3 months premature. Thus the lateness seems to be due to the fact that the nervous system is not quite 'done' when the child is born and has nothing to do with blindness. Severe deficit, irremediable.