Parents are only as happy as their least happy grown child. Research suggests one adult child who is struggling can weigh on a parent for years, and the other kids’ successes don’t make up for it.

Picture a family dinner. One son just got promoted. A daughter is happily married with a new baby. But across the table is the youngest, out of work again, going through a divorce, maybe struggling with something they don’t talk about.

The parents smile through the good news. But the worry they take home that night is about the one who’s struggling. There’s an old saying for this: a parent is only as happy as their least happy child. Research suggests it’s more than a saying.

What the study found

In 2012, a team led by Karen Fingerman, then at the University of Texas at Austin, published a study in the Journals of Gerontology on how grown children’s ups and downs affect their parents. The researchers interviewed 633 middle-aged parents, aged 40 to 60, about each of their adult children, more than 1,300 in total.

Parents described any problems each child had faced in the previous two years, like divorce, job loss, health problems or trouble with the law. They also rated how successful each child was in work, education and relationships, and reported on their own well-being.

The researchers expected that having successful children would cushion the blow of having one who was struggling. That’s not what they found. Having even one child with problems predicted poorer well-being for the parent, and the more problems across the family, the worse parents felt.

Why success doesn’t balance it out

Successful children did matter. Parents with several highly successful children reported better well-being. But having one successful child didn’t seem to offset the effect of a child who was struggling. As Fingerman put it, it takes many successful children to offset the negative consequences of one child with problems.

Fingerman suggested several reasons. Parents may simply feel their children’s pain. Struggling children may also need more time, money and support. And parents may see their children’s lives as a reflection of their own parenting, so a child’s difficulties can feel like a personal failure. As she noted, parents have a deep investment in grown children after decades of raising them.

This is in line with a broader pattern in psychology: bad experiences tend to affect us more strongly than good ones of the same size. A worry about someone we love can easily crowd out a dozen pieces of good news.

Aristotle’s uncomfortable answer

Philosophers have long asked whether our happiness can depend on things outside our control. Aristotle, writing more than 2,300 years ago, gave an answer that many people find uncomfortable. He argued that a good life needs some external goods as well as virtue, including friends, good health and good fortune. He went further, suggesting that someone with thoroughly bad children or friends was unlikely to be fully happy.

Aristotle even asked whether the fortunes of our children and descendants could affect us after we die. His careful answer was that they do touch us, but only slightly, not enough to make a happy life unhappy. For a living parent watching a child suffer, though, the effect is clearly much stronger.

On this view, a parent’s distress over a struggling child isn’t a weakness or a failure to “let go.” It’s what happens when someone’s happiness is tied up with the lives of the people they love most.

The Stoics offer another way

The Stoic philosopher Epictetus took almost the opposite view. He taught that we should separate what is in our control, our own thoughts and actions, from what isn’t, which includes other people’s lives. For Epictetus, other people’s choices and misfortunes, even our children’s, belong in the second category.

That doesn’t mean Stoics thought parents shouldn’t love or worry about their children. Epictetus was famous for urging people to remember, even while kissing their child, that the child is mortal. His point was not coldness but realism: love fully, but don’t stake your peace of mind entirely on things you cannot control.

For parents of a struggling adult child, this offers a possible middle path. You can keep caring deeply and keep helping where you can, while also recognizing that your child’s life is ultimately theirs to live.

Living with the least happy child

The Fingerman study was a snapshot, not a long-term tracking study, so it doesn’t show how long the effect lasts. But anyone who has watched a grown child struggle knows how persistent that worry can be.

There’s no simple fix. What the research and the philosophy both suggest is that a parent’s pain over one child’s difficulties is natural, common and not a sign of failure. Recognizing that can take some of the guilt out of it.

It may also help to notice the good news without feeling guilty about enjoying it. The successful child deserves celebration too, and a parent’s happiness for one child doesn’t betray the one who is struggling. Both feelings can sit at the same table.