Catalyst or Reporter

Today in TV History: 1997 - The television series "Ellen" made TV history when its lead character "came out" as a lesbian.

This brought about the following question for me. Is TV a catalyst for change? As in, does Ellen coming out as a lesbian as a character on tv spark a change in social acceptability of homosexuality. OR Is TV merely a a commentary on the change already happening within the social climate?

I want to hear your opinions... this isn't a question of whether or not you think homosexuality is acceptable- that is merely one example of a social issue that was brought out into the viewership... the question is TVs role in changing or commentating on social change.