My DD is a little older and displays this behaviour a little now. They have not yet learnt the concept of sharing, just understanding that they can own things, and fear others taking them away.
Saying that, my DD is currently unwell and is more prone to pushing/snatching get upset/angry when someone, in particular her cousin 3 months younger takes something she is either playing with, or she wants, than when she is well. So, maybe a comfort thing? Frustration perhaps at pain and also having to cope with a swine nicking a toy?! I think teething can effect behaviour much more than I thought at first. DDs molars were extremely painful, and she suffered a lot with them, more angry, more upset, more clingy. As soon as they were through, her behaviour settled lots.
We have started to introduce the concept of sharing to DD. I do find it funny although I should not when DD goes up to her cousin, snatches a toy and goes 'Shlare' to him!!! If she does not get her own way she gets very very upset, saying 'shlare, shalre' and crying!!!
I doubt if it is a significant element of his personality. I think it is a learning point, developing independence, understanding of the world, objects, their role in the world around others, coupled with other things such as teeth pain.
Hope that helps, from my perspective at least.