title: Inbreeding is associated with lower 2D: 4D digit ratio.
abstract: OBJECTIVE
  While consanguineous marriage has been shown to result in a small increase in risk of recessive Mendelian disorders among offspring, far less research has been conducted on the effects of inbreeding on complex traits. These effects, thought to result from increased developmental instability due to loss of heterozygosity, are expected to be found more pervasively than rare recessive Mendelian traits and are expected to result in increased developmental noise. Here, we test for a direct effect of inbreeding on 2D : 4D, a putative indicator of prenatal hormonal environment.
  
  
  METHODS
  We compared the 2D : 4D ratios of 122 male and 108 female consanguineous (children of first cousin marriages) high school and university students to those of 142 male and 122 females controls.
  
  
  RESULTS
  Across hands and sex, consanguineous parentage was consistently associated with lower, more masculine-typical, digit ratios. Digit ratios were 1.3-1.9 times more variable among the consanguineous group than the control group. While socio-economic status cannot explain the effects seen in our data, we found that lower, more masculinized, digit ratios were associated with lower family income.
  
  
  CONCLUSIONS
  Our results suggest that consanguineous marriages are associated with a fetal environment that influences morphological development and may have associated behavioral sequelae.
authors.affiliation: Faculty of Literature, Department of Anthropology, Cumhuriyet University, Sivas, Turkey.
authors.forename: Baris
authors.initials: B
authors.lastname: Ozener
authors.forename: Peter L
authors.initials: PL
authors.lastname: Hurd
authors.forename: Izzet
authors.initials: I
authors.lastname: Duyar
mesh_terms: D000293:Adolescent; D003241:Consanguinity; D005260:Female; D005385:Fingers / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D012923:Social Class; D014421:Turkey; D055815:Young Adult