Mr W (11m0w) noticed differences between me and DW about two weeks ago when we were all in bed one morning. At that time he compared our chests.

Today when we took a shower, he looked down there and then compared himself to us. He looked back and forth at us several times then looked at himself. You could really see the wheels turning. I think he knows there are differences and that he is the same as his dad, but I am not sure he has generalized to the entire population.