Will reading in poor light when you're young cause astigmatism?

I thought astigmatism is something that just is…it’s part of one’s genetic makeup. I got glasses for the first time when I was in 4th grade. We had just moved to Kansas from Florida, and at that time I attributed the problem to the fact that I’d tried to stare at the sun for a long time when we were in Florida. Dr. said No, that had nothing to do with it. I also read a LOT, from the moment I first learned to read before I started kindergarten.

What do ya’ll know about this? Dr’s?