Odd Year

On our walk we were discussing Thanksgiving wondering if it was the on year (all family) or off year (those without inlaws) when we remembered how Diane told us we would know. The big Thanksgiving will always be on the odd year as we are an odd family.
Mom in all sincerity asked "but how will we know if it is an odd year?"
At that point Rachel and Joan were on a roll, more rain than usual, hay crop, the extreme heat, yes this must be an odd year forget the number of the year.
OK Diane we need to come up with another way to know, every year in our family will be an odd year.