I think it could go either way with Clementine being Sawyers child. He did teach this woman the tricks of his trade. But, I am leaning towards it being his child. I think he had a gut instinct from looking at the childs eyes that it was his...a connection. I would imagine in his line of business he is pretty good at sizing people up..... But, he sure didn't pick up on Bens bluff.....which I think he might have if he hadn't been so concerned about Kate.