Anonymous wrote:Early twenties. You had your chance.
Be really careful that you aren't interpreting generational differences as bad manners. If they're shutting down your diet talk, rejecting your comments on people of other races and cultures, etc., then it's not really bad manners. It's them standing up for something they believe is really important.
If it's something like rejecting your new partner, well, it means they don't like that person and they don't have to. Stop trying to force "blended family" and they may stop being intentionally rude to make the point. I had to do this with my mom for a while.
Without any more context from OP, I agree with this.
By their early twenties, Regardless of the Situation, a young adult should know how and when to: Say thank you, Be polite with company, Dress apporpriately for the occasion, Excuse themselves from a room or a situation, Communicate their preference or ideas on a matter or topic with composure, Shut down a conversation they do not want to engage in.
If by manners OP you're talking about behaving like some Martha Stewart apron-wearing clone, that time has passed.