As far as I recall, my brother and I were never encouraged to believe in Santa Claus. Not in any actual buying-it kind of way. In fact it strikes me as odd that parents perpetuate the ruse, knowing it will be busted eventually by rumors at school. After all, if their kid is the one who most staunchly defends his parents' word, he'll be the laughing stock of the place---the last one to stop believing in Santa. But I guess the innocence/ignorance naturally growing into learning not to accept everything one's folks say works well in some ways. And the joy of myth is not lost on me. There's probably a much better chance than I used to think there was that I'd be a perpetuator of Santa, were there a kid around to fool or not.
Robbie & I, the way I remember it, had a kind of wink-wink understanding that Santa was really our parents, and the goal became to get them to admit it. Or, better, to prove it. (Same thing, at that point, I suppose.) The first year I remember our attempting such a triumph involved comparing Santa's handwriting in his cookie thank-you note to samples of each parent's hand. We found a citable similarity, but, in the face of their denials of it, were at a loss to establish our case. The next year Santa wrote distinctly differently from either.
But one year Santa brought us a Monopoly game. A few months later I asked my mother, "Where'd you buy the Monopoly game?" --- so pointedly casual I was probably dripping with it. When she answered "Western Auto," I had 'em. QED. Ha. Yeah.
It was like being confirmed in the church of secular humanist realist rationalist relativist agnostic philosophical academic intellectual heady thinky cogitatin' atheism.