Quote Originally Posted by Crocodile View Post
the kids grow up that way and when they realize they have a speech defect, it's most likely too late to be corrected.
In most cases (if it's not caused by physiological reasons) it's never too late to be corrected. I corrected my [ʁ] at the age of 23-25, it wasn't that hard actually - you just have to always keep track of what you say and not be shy to sound funny when trying to pronounce [r] correctly.