I knew he wouldn't understand so I tried to make the question as simple as I could and have tried in several different ways to ask it - "What would you like Santa to bring you?" "Are there any toys that you would really like to have?" I have even gone through catalogues like Mulberry Bush with him, trying not to lead him but to see if he spots anything that he would really like. He loves looking at the toys and pointing out the ones he has or that are in school but never once has expressed a wish to own any of them.
I don't really have any behavioural or developmental concerns for him but I do find things like this strange as I remember his older brother had long lists of things he wanted at this age. DS2 does love getting presents and always opens them with wonder and surprise - he is a delight to buy for because he will play for hours with whatever he is given.
I'm not even stuck for ideas on what to buy him as I know that he loves board games and puzzles - anything that he can engage the whole family into playing with him.