Regular conflict with family hasslers accelerates biological aging by up to nine months per added person, per a new study.

A new study finds that regularly interacting with difficult people, or "hasslers," especially family members, is linked to faster biological ageing—each additional hassler associated with a 1.5% increase in ageing rate and roughly nine months of added biological age. Analyzing over 2,000 adults in Indiana, researchers found that chronic stress from negative relationships correlated with poorer mental and physical health, though the effect was strongest in family ties and not seen with romantic partners, possibly due to emotional support. While causation isn’t proven, the findings suggest long-term exposure to high-conflict relationships may raise risks for age-related diseases.