We are living through one of the most extraordinary demographic changes in history: the dramatic increase in the human life span. This means that the amount of time children spend in the home with their parents is only a fraction of the shared lifetime they will have together. Indeed, after our offspring reach age eighteen, we are likely to have thirty, forty, or even fifty more years to go in the relationship. Our sibling ties may now last ninety or more years. The huge “longevity bonus” means that our family relationships can affect us—positively or negatively—for many decades.
