A review and meta-analysis of the heritability of specific phobia subtypes and corresponding fears

• Data on the genetic liability of fears and specific phobias are scarce.
• Heritability estimates of fears and specific phobias fall within a range of 0–71%.
• The category of blood–injury–injection fears and phobias has the highest heritability estimates.
• Phenotypic variance can mostly be explained by additive genetic and unique environmental effects.

Evidence from twin studies suggests that genetic factors contribute to the risk of developing a fear or a phobia. The aim of the present study was to review the current literature regarding twin studies describing the genetic basis of specific phobias and their corresponding fears. The analysis included five twin studies on fears and ten twin studies on specific phobias. Heritability estimates of fear subtypes and specific phobia subtypes both varied widely, even within the subtypes. A meta-analysis performed on the twin study results indicated that fears and specific phobias are moderately heritable. The highest mean heritability (±SEM) among fear subtypes was found for animal fear (45% ± 0.004), and among specific phobias for the blood–injury–injection phobia (33% ± 0.06). For most phenotypes, variance could be explained solely by additive genetic and unique environmental effects. Given the dearth of independent data on the heritability of specific phobias and fears, additional research is needed.