when and why did the parents television council start?

Answer 1

1995. Because many parent objected (and still object) to the content of daily primetime television show and commercial content - the violence, sexual innuendo and outright sex, etc.

"The Parents Television Council was founded in 1995 to ensure that children are not constantly assaulted by sex, violence and profanity on television and in other media."
http://www.parentstv.org/PTC/aboutus/main.asp