Couples that get divorced later in life when their children are already adults was once a rarely studied field—particularly the effects on those adult children and their relationships with one or both parents. In the past decade, as rates for these so-called “twilight divorces” or “grey divorces” have steadily grown, many scientists have been studying the effects on family dynamics and made some interesting discoveries.

“Today, roughly 36% of people getting divorced are 50 and older, compared...