Genetic and environmental contributions to humor styles: a replication study.

One thousand and seventy three pairs of adult monozygotic (MZ) twins and 895 pairs of same sex adult dizygotic (DZ) twins from the United Kingdom (UK) completed the Humor Styles Questionnaire: a 32-item measure which assesses two positive and two negative styles of humor. MZ correlations were approximately twice as large as DZ correlations for all four humor styles, and univariate behavioral genetic model fitting indicated that individual differences in all of them can be accounted for entirely by genetic and nonshared environmental factors, with heritabilities ranging from .34 to .49. These results, while perhaps not surprising, are somewhat at odds with a previous study that we conducted in North America (Vernon et al., in press) in which genetic factors contributed significantly to individual differences in the two positive humor styles, but contributed far less to the two negative styles, variance in which was instead largely due to shared and nonshared environmental factors. We suggest that differences between North American and UK citizens in their appreciation of different kinds of humor may be responsible for the different results obtained in these two studies.