Parents INSTINCTIVELY knew how to raise children, then Spock wrote his book and the 60's generation women bought the book, followed every word...and VOILA! RUINATION!!
Instinct does not have a rational foundation, nor is it an appropriate source for a rational plan to teach and develop the capacities of a sentient rational being. It's not rational to follow the directions in a book regarding child rearing blindly. Regardless, it is not logical to conclude that the children of said parents did not become capable rational actors. It is certainly not true that they are all "ruined".