A lot of authors get very nervous about writing about people they know. There is the feeling that people will recognize themselves or worse be offended. Writing about one's family is especially taboo to a lot of people. When my second novel hit the stores I was surprised my mother took offense to some of the scenes in Mica Highways. There was insanity in the novel and in my own family there had been some cases. No surprise huh?
But I was amazed she would draw the line and it would bother her that people long dead might be inferred to have had mental problems. There were several very terse letters and then it sort of just blew over. Siblings weighed in and words were exchanged but the book was out. And I as pointed out many times, the story was fiction.
Of course when we write we must put all these ideas aside and just write. Easy thing to say, hard to do for some people. But characters cannot be copyrighted even by family. The minute we breathe we all become potential characters for some novelist or short story writer somewhere. As long as he or she has the will to tell it like it is.