IMPOSSIBLE QUESTION:
10% of all people have something that they are not willing to share; what is it? 

It’s not an object.  It’s not something you buy at a store. 
It’s often something that has been in the family for a long time

ANSWER:
10% of all people have a recipe for something that they are not willing to share with anyone!    

Congratulations to Isaac Van Winkle for being the first to answer the Impossible Question!