My parents never really talked to me about masturbation much, but it was never presented as a bad thing. I once got a minor yeast infection when I was twelve or thirteen, and my mother said, "How should I put this delicately... have you been masturbating?" Real delicate, mom.
But she was just telling me to make sure my hands were clean when I masturbated and to cool it until the infection went away, not saying that masturbation caused the problem.
I read about the blindness myth in a Dr. Ruth book, and the author immediately debunked it as a load of crap. Along with myths about masturbation killing brain cells or making girls pregnant. Seriously, who thinks up this stuff???