No matter what age you are, you, your siblings, and your cousins will always be seen as "the kids" at the family Christmas gathering. This likely means you'll always have your own table. And even though you're 20-somethings now, you might not see each other very often, so when you're finally together again, you have a ton to catch up on. These are definitely a few of the things you still talk about at the "kids' table"with your cousins.
Celebrating the holidays with your extended family is always the best, because it means you and your siblings are able to spend quality time with your cousins. (And let's be honest: They're the coolest.) They already know everything about you and your family. They laugh at all of your dad's corny jokes, and are right by your side to get through your relatives' prying questions together. You can drink some wine (if you're 21 or over), and gossip about your family while your parents all catch up, too.
No matter how much time passes, or even who gets married, you and your cousins will still be passing the time at the "kids' table" on Christmas Day. You really wouldn't have it any other way.