Twelfth night is Epiphany. Gifts were given then, in commemoration of the gifts given by the Magi. It's been a while since 2yr old boys were slaughtered though..... (side story ~ the Star appeared when Jesus was born so it would have taken the Magi a while to notice it and find Him. They stopped off at Herod's place on the way, which is why, when he realised he'd been tricked, had all the boys of 2 and under killed).

To get people into the habit with the new calendar (when 11 days were 'stolen' to bring the calendar into line) it was put about that it was unlucky to have your decorations or your feasting after that day. It probably was too.. the local priest and authorities would come and punish you for celebrating at the wrong time. The Orthodox churches still celebrate Christmas on 6th January.

The season of Christmas doesn't end until Feb 2nd, Candlemass, so you can keep your decorations up until then if you like!

There are lots of Twelfth night traditions around, but I can't lay my hand on the book at the moment.

LTS