Evidence from studies of families and twins presented by several investigators suggests that some neuroses, such as anxiety neurosis, have an important genetic component whereas others, such as hysterical neurosis, may have none or a relatively unimportant genetic component. The heritability takes the form of a genetic predisposition that culminates in clinical neurotic symptoms only when the person is subjected to the proper set of environmental stresses. Psychological test studies show significant heritabilities of various personality traits, including "neurotic tendencies," and animal studies show that rats can be selected for "emotionality" or "nonemotionality." Evidence suggests the hypothesis that the genetic basis is complex polygenic system in which some genetic loci are additive while other loci function via various genetic mechanisms.
Miner GD. The Evidence for Genetic Components in the NeurosesA Review. Arch Gen Psychiatry. 1973;29(1):111-118. doi:10.1001/archpsyc.1973.04200010080014