I think as long as there have been sentient people, people, especially in families, have not been talking about certain things.
My mother just ignored anything she didn't like so if I bought clothes decorated room, anything and she didn't like it. Silence. If she liked it, she would say so. She was also totally uncomprehending about things I did, study for pleasure rather than job improvement. so I generally didn't talk in any detail about any course I was doing with her.
I do not think I tiptoe around DC particularly, anymore than anyone else but I do think, as parents, we need to realise when our children are grown-up and entitled to have their own views, opinions and life styles, whether we agree with them or not. We should treat these with the same respect we would treat anyone else who acted and thought as they do.
Obviously there will be times when our DC do things that either disrespect us (*Anya*, above) or are actively harmful to themselves and/or others, then we need to speak up and accept the flak that will follow, but no different than one would do with a friend.