My parents are alive, but they are both so distant it's not far from them being dead really.
A few years ago my mother decided to tell me that she feels nothing for people and she always pushes people close to her away anyway, and my last communication with my father was apparently only so that he could try to guilt me into doing things for him (which doesn't work, being that was mostly absent in my life, and proved himself an unpalatable and manipulating person besides). Neither of them were in contact very often, to the point where they might not actually have known if I was alive or dead. I live hundreds of miles away from them after all.
It bothered me deeply for a few years. I was angry, because I felt entitled if not to their affection, for them to at least understand that I was having a difficult time. They both seemed to think I owed them the same but never gave much thought to the stress and logistical difficulties I've had in life. Like I was just supposed to be there at their disposal. I got over it in the end. They aren't the family I would like; I did think they were nicer people than this but I guess I was wrong. When they die I suppose it will hit me again, but I've already had to go through a process of shedding my feelings for them.