Season of birth variations in the temperament and character inventory of personality in a general population

The authors analyzed by multiple logistic regressions the Temperament and Character Inventory (TCI) for 2,130 individuals taking part in the Betula prospective random cohort study of Umea, Sweden. The personality dimensions were correlated significantly with age and gender. The data were stratified according to age, gender and the season of TCI measurement. By the median split in each stratum, a high-value group and a low-value group were obtained for each of the personality dimensions. Those born during February to April were significantly more likely than those born during October to January to have high NS (novelty seeking) among women, particularly the subscale NS2 (impulsiveness vs. reflection), and to have high PS (persistence) among men. Temperament profiles also showed season of birth variations.