Nearly 30% of people have at least one "hassler" in their social network who makes life difficult.

Each hassler is linked to a 1.5% faster pace of biological aging and roughly 9 months of extra biological age.

Family hasslers, like parents, siblings, or children, leave the deepest biological imprint.

Women, people in poorer health, and those with adverse childhood experiences are more likely to have hasslers.

Your Body Keeps the Score... of Bad Relationships

Most of us know intuitively that difficult people are stressful. The coworker who constantly stirs up drama, the parent who turns every phone call into a guilt trip, the sibling who makes every family gathering tense—we feel the weight of these relationships. But a new study published in PNAS in February 2026 suggests the toll goes far deeper than feelings. It reaches all the way down to your DNA.

A team of researchers led by Byungkyu Lee (NYU) and Brea L. Perry (Indiana University) studied more than 2,300 adults in Indiana, ranging in age from 18 to 103. They collected saliva samples and used cutting-edge "epigenetic clocks"—tools that measure biological aging by reading chemical modifications on DNA—to assess how fast each person was aging at the molecular level. They also mapped out each participant's social network in unusual detail, asking not just who supports them but also who hassles them.

The results were striking. Each additional person in a subject's network who created stress in their life (what the researchers called a "hassler") was associated with 1.5 percent faster biological aging each year. Each hassler was also associated with being about 9 months older, biologically speaking, than peers of the same chronological age. To put........

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