I grew up knowing that Santa didn't exist. My parents had to then explain to me that I couldn't tell certain kids about this because their parents wanted them to still think Santa was real until they were a bit older. I still remember being quite shocked that these parents were lying to their kids, along with grandparents and other family members, and then expecting even me to join in. I was further shocked by the fact that most of these kids never worked it out themselves and had to eventually be told by their parents or a group of their friends (being told by one or two friends usually wasn't enough.)
So, while I never experienced the shock of finding out that Santa wasn't real, watching these parents lying to their kids about Santa again and again certainly left a strong impression on my young mind.
That is a good point.
Related on OB: Lying to Kids The Third Alternative
My wife and I are planning to have kids, so of course we've been going through the usual sorts of debates regarding upbringing. We wondered briefly, will we raise our children as atheists? It's kindof a cruel experiment, as folks tend to use their own experiences to guide raising children, and both of us were raised Catholic. Nonetheless, it was fairly well settled after about 5 minutes of dialogue that atheist was the way to go.
Then we had the related discussion of whether to teach our children about Santa Claus. After hours of debate, we decided we'd both have to think on the question some more. It's still been an open question for years now.
Should we teach kids that Santa Claus exists? This isn't a new question, by any means. But it's now motivated by this thread about rationalist origin stories. Note that many of the posters mark the 'rationalist awakening' as the time they realized God doesn't exist. The shock that everybody, including their parents, were wrong and/or lying to them was enough to motivate them to pursue rationality and truth.
If those same children were never taught about God, Santa Claus, and other falsehoods, would they have become rationalists, or would they have contented themselves with playing better video games? If the child never realized there's no Santa Claus, would we have a reason to say, "You're growing up and I'm proud of you"?