What's the name of this movie I'm thinking about?

What's the name of this movie I'm thinking about? It's based on like the early 1800's or early (ya know, those movies based on the past, with people who dress like the founding fathers and crap, like old English/Europian I guess). I think it was based in Europe. It has to do with some royal/rich family with some woman who falls in love with this one guy. They have kids, but later he discovers the woman had children by her brother, and not him. The brother is like a horny dog, and goes around doing the maids/servants. He also got into a debate on evolution in regards to dogs and wolves. At the end of the movie I believe the guy with the misfortune ended up going away with some other woman he cared deeply for. Any ideas?