What does Silas realize about the Morton brothers after they confess what they have been doing to Sheriff Chalfont?

After the Morton Brothers confess what they have been doing to Sheriff Chalfont, Silas realizes how young the brothers are. He believes they are not yet 18 because of the tufts of hair growing on their chins. They are big and have soft faces and delicate lips. They are not monsters; they are fools.