Seyed Sepehr Hashemian, Senobar Golshani, Kimia Firoozabadi, Ali Firoozabadi, Christian Fichter, Kenneth M Dürsteler, Annette B Brühl, Habibolah Khazaie, Serge Brand
BACKGROUND: There is sufficient evidence that the index-finger-to-ring-finger-ratio (2D:4D-ratio) is associated with testosterone and estrogen exposure during the fetal stage. More specifically, a lower 2D:4D-ratio (that is; a shorter index finger, compared to a longer ring finger) was associated with a prenatally higher testosterone and lower estrogen exposure during the first trimester of the fetal stage. At a behavioral level, among adults, a lower 2D:4D-ratio was associated with a higher competitive performance among both female and male professional athletes, and with personality traits such as higher scores for mental toughness, dark triad traits, and aggressive behavior, and internet use disorder...
December 11, 2023: Journal of Psychiatric Research