Dear LJ,
Holidays have a lot of history attached to them and unresolved relationship issues tend to sneak through the cracks.  Unfortunately for many reasons spending time with family at the holidays can create a great deal of anxiety.  I’ve heard of people ‘regressing’ when they are back in the family house with siblings, etc. as we start to play out old roles and ways of relating to one another.
The only thing you or anyone can control is their own attitude and reactions.  My advice is to set an intention the night before the holiday as well as the morning of and remember that alcohol is an added dynamic that escalates any family issues!