What do you wish that everybody knew?
Unless you know your parents, you will never know yourself. Simple stuff, yet vitally important. Sit them down over a period of years and take their life stories. Every detail, every bit of wisdom or folly, everything. Compile them into volumes - The Book of Mom and The Book of Dad. Print copies and keep in family for generations. If you do not do this, you have failed your family and humanity is all the poorer because of it.