How do genetic factors influence human life span?

Genetic factors significantly influence human life span, though the relationship is complex due to the interplay between heredity and environmental influences. Research indicates that longevity is partially heritable, as evidenced by studies showing that individuals with long-lived parents and grandparents tend to have longer life spans themselves. Furthermore, monozygotic (identical) twins exhibit more similar life spans than dizygotic (fraternal) twins, reinforcing the role of genetics.123

At the cellular level, life span is regulated in part by telomeres—repeated DNA segments at the ends of chromosomes. Each time a cell divides, these telomeres shorten; once they reach a critical minimum size, the cell can no longer divide and eventually dies. Genetic variations in the TERC gene, which encodes a component of the enzyme telomerase, can disrupt telomere maintenance. Such mutations are associated with reduced telomere length and an accelerated rate of biological aging, increasing susceptibility to age-related diseases. Additionally, genetics influence life span through inherited susceptibility to specific conditions, such as cancer and heart disease.431