I saw my first musical when I was 2. It was GUYS & DOLLS. I knew every word to every song by the time I was 3. JCS was also a favorite in my house. When I was 4, my brother (who was 6) and I choreographed JCS in my basement using legos, toy soldiers, Belle as Magdalene, an alien as Judas, BatMan as Puntious Pilot, etc. And we both knew all the words.
I think theatre is good for kids, if they can sit through it! Some annoying kids who are not interested at all make your theatre experience a disaster. When the kid starts to cry and kick your seat and say every 2 seconds "Mommy I have to go to the bathroom", etc., it's annoying.
And King Lear?? Ok- that's just weird.
I have my books and my poetry to protect me...