Marianne Walsh and her sister, Megan Putman, keep track of whose kids their mother babysits more. They also compete with each other over parenting styles (Ms. Walsh is strict, Ms. Putman is laid back) and their weight.
“My kids play more instruments, so I am winning in piano,” says Ms. Walsh, 38, the younger of the two by 13 months. “But she won the skinny Olympics.”
Adult sibling rivalry. Experts say it remains one of the most harmful and least addressed issues in a family. We know it when we see it. Often, we deeply regret it. But we have no idea what to do about it.