My kids are 2 and 3 so of course they believe in santa. I have a SIL that when her oldest asked her the "is it true" question. She explained it to him but told him that it was his responsibility since he was the oldest to help keep it alive for his 3 younger siblings. And if he didnt all he would be finding under the tree that year was clothes lol. Needless to say he decided he didnt have to belive but his younger siblings did and he didnt want nly clothes for christmas lol.