@thebluewizard - I suspect my mom didn't get her folic acid, which is the common cause of neural tube birth defects. Maybe Valerie's too. Now we know about that.
Yes, I walked on my toes and did not speak clearly until about 18. In 1962 They put me in what was then called the "retarded" class in 1st grade - no examination. When my parents finally figured that out, they lawyered up, but I still had to be taught to read by an aunt over the summer.
Thank goodness things are better today.