They are both fine, but they have slightly different connotations. The first is talking more about how your parents are right now, and the second more about how they might be going forward.

It seems that both are possible in different cases: wish + past simple is used to express that we want a situation in the present (or future) to be different. I wish I spoke Italian. (I don’t speak Italian) wish + would + bare infinitive is used to express impatience, annoyance or dissatisfaction with a present action. Example, I wish you would stop smoking. (You are smoking at the moment and it is annoying me.)

You can say both!