Some people are simply more hopeful than others, and a good part of that difference is written in their genes. A twin study puts the heritability of hope at 41 to 43%, with the rest explained by each person’s own life experiences.
The study was carried out by Sereena Dargan and Julie Aitken Schermer of the University of Western Ontario in Canada. It was published in Personality and Individual Differences online on May 20, 2025, and appears in the journal’s October 2025 issue.
Comparing identical and fraternal twins
Psychologists define trait hope as two kinds of goal-directed thinking. Pathway thinking is the ability to see routes to a goal, and agency thinking is the drive to follow them.
The researchers used data from the TwinsUK registry, collected through self-report surveys in 2022. The sample included 917 same-sex adult twin pairs: 637 identical pairs and 280 fraternal pairs. Participants averaged 61 years of age, ranged from 21 to 90, and were mostly women.
Each twin completed the eight-item Trait Hope Scale, rating statements such as “There are lots of ways around any problem”. Because identical twins share all their genes and fraternal twins about half, comparing how similar the two kinds of pairs are lets researchers estimate how much of a trait comes from genetics and how much from the environment.
Personal experience matters more than family
Identical twins’ hope scores were more than twice as closely matched as those of fraternal twins, with correlations of about .43 to .45 versus .16 to .18.
Statistical models attributed 41 to 43% of the variation in hope to additive genetic effects. The remaining 57 to 59% came from the unique environment, meaning influences and experiences that differ between siblings.
The shared family environment, the upbringing twins have in common, contributed essentially nothing. The best-fitting model left it out altogether.
The two parts of hope were slightly less heritable on their own. Genes explained 36 to 38% of pathway and agency thinking, with the unique environment accounting for 62 to 64%.
Women scored slightly lower on hope than men, but age made no difference, and the genetic picture stayed the same whether the analysis included both sexes or women only.
How it compares and its limits
The estimate is a little below the only earlier twin study of hope, which found a heritability of 53% in American women twins. Both studies found that genes and personal experience, not shared upbringing, explain the differences.
The authors note that men made up only about 10% of the sample and fraternal pairs were underrepresented, which may limit how well the findings generalize. The classic twin design also assumes identical and fraternal twins grow up in equally similar environments.
The result leaves real room for change. With more than half of the variation linked to individual experience, hope remains a trait that life events, and targeted interventions, can still shape.
Study Details:
- Title: The heritability of hope: Exploring genetics and the environment as sources of variation
- Authors: Sereena Dargan, Julie Aitken Schermer
- Journal: Personality and Individual Differences
- Publication Date: May 20, 2025 (online); October 2025 issue
- DOI: 10.1016/j.paid.2025.113260