Thanks syedshahmir, our kids are truly our masters.
And I understand that happiness is the combination of all other emotions, anger, sadness, fear and joy are all (in my opinion) important.
Just look at Tahiel, he cries when he is hungry, without that sadness he would starve, he screams when he is upset, that way we can know that he is feeling unconfortable, and he gets frightened if an unknown force appears, thats a survival instinct coming through. I think that only because he is so open to express every emotion, his laughter is so pure.