I refused to pass on the Santa BS story to either of our kids, but it is so ingrained into the culture, the kids pick up on it and choose to buy into it because it is to their advantage to believe in a fat guy that gives them a bunch of cool shit. When you point out that it's a BS story, they simply refuse to believe you.
This is quite common.
My childhood experience is that I bought the story foisted on me by my parents, and when I figured out it was a hoax, I was pissed and felt humilliated. At this very time, I was being indoctrinated into Xianity in Sunday School, which I recognized as being exactly the same con game...... grown-ups attempting to extort 'good behavior' from me via carrot stick and badly written fairy tales.
I immediately rejected religion entirely, (won't get fooled again)at 7 years old, which worked to my advantage because I was terrified by the hell fire threat.
I've an Atheist ever since, despite growing up in a Missouri style evangelist environment.
Santa Claus and Sunday school is what made me an Atheist.
How confusing is that?
Have fun, I have really enjoyed being a parent. And I'd also recommend explaining sex the first time they ask.