weesin I disagree with you because for 1 the quote doesn't say "can sometimes can", for 2 it is sorta true that "people with the loudest laughs and the biggest smiles have had the most painful past", and for 3 the author doesn't have to have researched about this they may have experienced it first-hand. By the way, there should be a comma because if you knew that the purpose of a comma is for you to take a pause, the quote is very reasonable and sounds a lot better with the comma, than without! When I first read this it touched me and I know dang well you probably couldn't do better, so while you are over here trying to be a critic you might as well criticize yourself.