Maybe he thinks that overall life is pretty sweet so he doesn't need to feel sad kwim? I mean, most kids get pretty snakey when you take a toy away or they can't have something, but rarely will they get sad. They just don't seem to find themselves in the situation where they might actually feel sad. I can't ever recall a time when any of mine have been truly sad because they just haven't been exposed to any situations where they would truly feel sad. When my Nan died years ago, DS1 wasn't even 2 and DD1 was only 11wks old and DS was too young to understand. He knew I was sad, and gave me extra cuddles and kisses, but he didn't show it himself.