The holidays can serve as a wonderful lens because we often leave one intense environment (work) and enter another (extended family).
That shift is worth noticing. What stories come up for you as you enter your childhood home? What patterns reappear? Who is bugging you? Is it the same people who bugged you the last time you were there? Is it something new? Or, perhaps, is the tension a little less this time?
This works with in-laws, too. Sometimes we can look at someone else's family and not understand all the drama. Or maybe we think that our partner should be behaving differently, because we know then as an adult, and not as the child he or she was when these patterns were formed.
It's a mistake to walk into these situations with an idea that "I'm going to be calm" or "I'm not going to let my sister get to me." There is no goal.
But we can notice where we are, and be all right with that.