If you are at a party, and you spot one of your children across the room...
Leave...you are officially too old to be there.

If you are at a party, and you spot one of your parents across the room...
Leave...you are definitely not old enough to be there.

If you are at a party, and have left because of either sign #1 or sign #2...
then come home to find your child or parent has left that same party for the same reason, then head out together and start a party of your own. You aren't as different as you thought.