I think I was in junior high when it really sank in. The man I called grandpa had a different last name than two of my uncles. I think you don't really notice because your grandparents are grandpa Smith or Grandpa Jones and your aunts and uncles are uncle Tom or aunt Mary.
It happened in the early 30's and my mom was all of nine. Her dad probably would have survived the pneumonia but he had TB, too and these were the years before antibiotics and the social safety net. The man I knew as grandpa promised to look after the family of his closest friend. They married before too long and had a son together. He treated all the kids the same, hugged them when they needed it and even if they didn't. Helped all his sons when they needed it and stood up for the girl he called a daughter when she started her own family.
We all called him grandpa and after over twenty years I still miss him. I hope he's found a place on the bank to fish. With any luck all the cats, and other pets they had over the years are helping out.