Twins who share all their genes are not much more alike in how funny they are than twins who share half. That is the surprise in the first twin study of humor production ability, the skill of actually making people laugh.
How funny people believed they were did run in families. The skill itself, measured by strangers judging the jokes they wrote, showed no significant genetic effect.
The study was led by Gil Greengross of Aberystwyth University, with Nancy Segal of California State University, Fullerton, Stephanie Zellers and Jaakko Kaprio of the University of Helsinki, Paul Silvia of the University of North Carolina at Greensboro and Claire Steves of King’s College London. It was published online in Twin Research and Human Genetics on July 7, 2025.
Cartoons, captions and 40 judges
The researchers recruited from the Twins UK registry in the summer of 2022. Of 17,100 registered twins, 3,332 took part. The final sample held 1,363 twins, 89.4% of them women, aged 21 to 89 with a median age of 66, including 448 complete identical pairs and 196 complete fraternal pairs.
Each twin wrote one funny caption for each of two captionless cartoons in the style of The New Yorker’s caption contest. In one, a wet bear works as a waiter taking a restaurant order. In the other, an estate agent shows a couple a house in space.
Forty judges from Aberystwyth and the surrounding area scored the captions from 1 to 5 without knowing anything about the writers, or even that they were twins. A statistical model then adjusted each person’s score for how harsh their particular judges were.
Twins also rated how funny they thought they were and how often they made others laugh, and gave the same ratings for their co-twin. They took a short three-question cognitive test and rated their own health.
What the genes did and did not explain
Self-rated humor, the cognitive test score and self-rated health were all moderately heritable. Judged humor ability was the exception: its additive genetic effect was not significant, and its variation was best explained by shared and unshared environment.
That runs against expectations. Studies of intelligence and creativity typically put heritability between about 0.40 and 0.80, and earlier work found genetic components in humor appreciation and humor styles.
The two measures of humor also barely agreed. Self-rated humor was only weakly correlated with judged ability, and a twin’s self-rating correlated at 0.48 with how their co-twin rated them. Men scored higher than women on self-rated humor, co-twin ratings, judged ability and the cognitive test.
The authors’ own doubts
The team stresses that a small genetic effect cannot be ruled out. Their post-hoc power to detect one was only 0.27, and they estimate a sample about six times larger would be needed to reach the usual 0.80.
They also note that writing captions on demand is artificial and demanding, especially for older people, that the judges were younger than the twins, and that only about 10% of the sample were men. Even the cognitive test showed practically no correlation with humor ability, which they call surprising.
The paper still poses a pointed question: whether the talent of comedians like Robin Williams or Billy Connolly has a genetic basis is something this study “could not identify.”
Study Details:
- Title: Heritability of Humor Production Ability: A Twin Study
- Authors: Gil Greengross, Nancy L. Segal, Stephanie M. Zellers, Paul J. Silvia, Claire J. Steves, Jaakko Kaprio
- Journal: Twin Research and Human Genetics
- Publication Date: July 7, 2025
- DOI: 10.1017/thg.2025.10010