I have no evidence at all that either of my parents knew about masturbation.
The only thing my father ever said about masturbation was to do it in the forest if I ever got lost.
Because someone is bound to find you if you are jacking off.
I think it was voice of experience.
Oh, yes it did! I assure you. 
As for me, amazingly, my mother decided to tell me the “facts of life” at age 4 because her mother had never told her anything related to sex. Which, of course, made no sense due to my age. Instead of it being helpful and informative, I spent my grade school years truly mystified by what the hell 69 was. And masturbation wasn’t any less so. What really helped was good old Judy Blume. If those girls were doing it, than it must be something worth checking out. So, those was my guide books and I figured out what I needed to know before (or by) junior high.
This thread is evidence of why sex education is best left to the schools and parents should stay the hell out of it.