So NC for this one and bear with me cos this sounds like the plot of a crap novel....
My mum has three children from a previous marriage - he was a highly respected professional man but massive issues with DV, raped her within their marriage, many, many dreadful things happened to her. She met my dad and they fell in love.
His parents (he was still living at home) loved her, but didn't want and didn't have the room for, three children who weren't their grandchildren in their little rented terrace with outside toiler. This being the suburban 1960s, what the neighbours thought was very much a thing. When the divorce came through mum and ex were offered 50/50 custody and mum considered it best and least disruptive for her children to leave them with their father in the family home full time.
So fast forward 60 years, and her first family would like to be be in contact with her. Mum is in her 80s, frail, early stages of dementia, and in sheltered accomodation, and she doesn't think she could cope with the emotional upheaval that it would cause her to resume contact - not to mention the possible disappointment for all parties after so long.
Seems they also want to have contact with me. Obviously we have the same mother but other than that we were brought up in different worlds, different backgrounds, different lifestyles. I'm not curious about them: I've grown up knowing about them but I don't feel that I'm missing a piece of my life. From what I hear of them we have nothing in common more than a shared biology. (That sounds snobby but that's not what I mean - let's say from what mum has been told they would not approve of my lifestyle.)
AIBU to want to leave sleeping dogs lie and to decline contact?