Ok I just noticed that The BBT makers cast a lot of short actors
see
Sheldon : 6'2 (tall)
Penny : 5'7 (tall for a woman)
Raj : 5'8 (Average)
Leonard : 5'5 (Short)
Howard : 5'4 (Short)
Bernadette : 4'11 (Nearly to the midget area)
Comment or you will end with a big Bang BANG