A recent post, protected so I won't bother linking to it, brought up a bit of how people treat anniversaries and holidays differently. I find I tend to recognize them, but I'm not too big on holding to exact dates for things. I think that came about from sharing, or perhaps not sharing, a birthday.
My sister and I have the same birthday, separated by five years. This wasn't planned, so we have been told. She claims, or at least once claimed, that somehow I had stolen her birthday. She is five years younger than I am, so I don't see how that could be.
The result was that when we were kids there had to be two cakes, at least. Generally what would happen is that we'd each have a cake on a weekend, and it would two different weekends. I forget how gifts were handled, but what I think happened was that we'd each get something on each weekend, probably by visiting different sets grandparents on each weekend.
The result of this is that I don't consider the exact date of my birthday to be important. I had to explain that once when someone sent me something and it didn't arrive on or before that date. The sender seemed to feel bad about it, but it simply wasn't important. That the sender thought to send at all, that was important. Even that wasn't necessary. It was just nice.
If I do remember a birthday - other than my sister's - it isn't because I really remembered it, it's because I looked at the calendar in the office. I made notes of folk's birthdays and wrote them down and now mark up the calendar before putting it up. Sometimes I still miss things. Nothing's perfect.
Last year Jay and I visited my folks for Thanksgiving and his folks for Christmas. My folks and my sister and I simply moved Christmas to Thanksgiving and that was pretty much that, no big deal. In fact, I rather liked that - it got things out of the way and I got (most of) my Christmas shopping done before the wretched "Christmas shopping season" which I find to be overcrowded and far too loud. It was amusing hearing the news reports on how the shopping was and such and not caring one little bit as it had been taken care of already.