I am the middle (girl) of 5 siblings: 2 boys, 2 girls, 1 boy born 8 years after the stair-step of the 50's. Our parents were great, and Dad was the disciplinarian. Mom hated conflict and always refused to deal with it. The biggest problem was the oldest being a bully (grew out of it) and the youngest girl being a brat (loved to stir up problems, tattle, etc. and grew up to be the only divorced sibling who changed jobs frequently due to conflicts in the office).
Fast forward. Dad died many years ago. Mom never reined in the family pain in the ass. The baby of the family devoted himself to taking care of Mom, I was the dependable one with the medical power of attorney and caregiver throughout years of medical problems, and the two other brothers helped with financial and house issues. Mom did have finances in order, a will and a trust, and thought she had prepared, but refused to deal with "stuff". She attached post-its and notes to her will and papers. $10,000 attorney's fees later, the 4 of us have long since vowed we don't have a sister. She came in at 2-3 a.m. the night of mom's Celebration of Life when everyone was asleep at their hotels and loaded a truck with stuff. She claimed 50% of the jewelry, and took first pick (the rest was divided among the 4 of us). She had already taken many, many things over the years and threatened to sue us all (yes, she's a corporate shark).
Bottom line to all parents: grow a spine and take care of grasping, self-centered behavior early and make a plan to continue beyond the grave when you know there's an issue.