February 13, 2026 — As America’s population ages, new research suggests the relationships people build over a lifetime may influence how well they age.

The share of senior citizens in the U.S. is projected to rise from 18.7% in 2025 to nearly 23% by 2050. At the same time, the percentage of children under 18 is expected to fall from nearly 21% to about 18.4%. With that shift comes growing attention on what supports healthy aging.

A study highlighted by Cornell University found that the cumulative effect of social advantages across a lifetime, from parental warmth in childhood to friendships, community involvement, and religious support in adulthood, may slow the biological processes of aging.

Researchers developed a measure called cumulative social advantage. It included supportive parental relationships, community engagement, faith-based support, and emotional support from friends and family. People who scored higher showed slower epigenetic aging.

Using DNA methylation patterns measured by epigenetic clocks, researchers found that some participants with stronger long-term social ties had biological ages that appeared younger than their chronological ages.

The study also linked stronger social networks to lower levels of chronic inflammation, including reduced interleukin-6, a molecule associated with heart disease, diabetes, and neurodegeneration. That finding suggests social connection may influence aging through measurable changes in the immune system.

Additional research published in the American Journal of Health Promotion reviewed 34 studies of adults 65 and older and found that social and interpersonal factors play a key role in physical activity later in life. Stronger social support was associated with higher activity levels, whereas loneliness and isolation were associated with lower activity levels.

Because physical activity is tied to reduced chronic disease risk, improved mental health, and better quality of life, researchers said efforts to promote healthy aging should prioritize strengthening social networks.