Parenting Methods

I noticed in class that a lot of people said that their parents have a different parenting style now than when they were younger. Some said their parents are more permissive now, and some said their parents are more authoritarian now. Personally, my mother was more permissive when I was a kid, and my father was more authoritarian. Now, it's the opposite. My mother is more authoritarian (but not so much), and my father is more permissive. I was just wondering why parents change their parenting method. Do they even actually change, or do we just think they change as we get older and go through different stages of life? Anyway, I feel that since one of my parents is permissive and the other is authoritarian, I get an overall sense of authoritative parenting from my parents. It usually seems bad to have an authoritarian parent, but in this case I get the better and correct balance of parenting.