Who wants to believe? Associations between digit ratio (2D:4D) and paranormal and superstitious beliefs

Associations of paranormal and superstitious beliefs with digit ratio (2D:4D) and absolute finger length (putatively indexing prenatal and pubertal-adolescent androgen levels, respectively), fluctuating asymmetry (FA; indexing developmental instability), and body measures at birth (indexing non-optimal fetal growth) were examined in a sample of 1118 adults. Higher (feminised) 2D:4D correlated with stronger beliefs in men, even when controlled for age, education, adult height and weight, and birth length and weight. Shorter (feminised) finger length correlated with more superstition among women, but not when controlled for the same covariates. Finger FA was unrelated to beliefs in both sexes. Shorter birth length (in men and women) and lighter adult weight (in women) were associated with stronger beliefs. Effects of 2D:4D on men’s beliefs were weak (1–3% attributable variance), but commensurable with those of known non-biological belief correlates (age: 1%; education: 2%). This evidence may be informative for narrowing down possible developmental pathways of paranormal and superstitious beliefs. Propensities contributing to sex and individual differences in these beliefs probably arise in utero, may partly be due to prenatal testosterone and other prenatal programming effects, but less likely due to pubertal-adolescent androgen action or developmental instability.