Using logistic regression controlling
for zygosity, sex, age at interview, interview form, and correlations within families, the level of standardized neuroticism strongly predicted risk of phobia (OR, 1.67; 95 % CI, 1.58 - 1.77; z = 18.55; P <.001).
Zygosity may have implications in a twin or multiple pregnancy,
for example, in cases of medical complications such as Twin - to - Twin Transfusion Syndrome (TTTS).