What's a sign that someone grew up poor?

Careful with their money yet willing to help someone that needs it, common sense which those that grew up with things handed to them do not possess and they most often work (ed) hard for what they have.

I grew up very poor and for the last 30 years have had my own consulting business, only work when I want and the weather is nice and make over $250k year. I didn't get there by being lazy and my college degree in education never had any thing to do with it but I had it paid for before I was out of college.

They wear gym cloths outside of the gym.

Looking up my family tree and finding three dogs using it.
(Rodney Dangerfield).

Having a million different uses and recipes with sandwich bread

they don't toss usable items into the trash

Far less trash in the trashcan (singular) than most.

Always worried about health insurance.

They eat fast food rarely