I know of a fellow pretty old, who wanted to sell his house, but his 2 children made it difficult by not cooperating, leaving big messes, etc. The children were 45-55 yrs old !
The fellow eventually sold after more than a year, by dropping the price drastically. He moved out to an apartment for just him, and let the buyers chase out the kids.
Another very old guy has his 55-60 yr old son living at home last couple of decades. He seems pretty normal except has no friends, which is not surprising as all his buddies have families/jobs etc.
Get them out early, or you will have to move out instead.