Variations in personality traits among adolescents and adults according to their season of birth in the general population: further evidence

Season of birth has earlier been found to be associated with adult suicidal behaviour and with adult turnover of monoamine neurotransmitters. A previous study on adults has also shown an association between season of birth and the personality scales of Cloningerʹs temperament and character inventory (TCI) in a general population. The temperament scale of novelty seeking, particularly among women, was significantly lower for those born during the period containing winter (October–January) in comparison with those born during the rest of the year. In a different study on adolescents, an opposite season-of-birth relation for novelty seeking was found among adolescents. In the present study, we explore the relationship between season of birth and personality assessed by the TCI, in an independent and non-overlapping cohort of 1145 subjects in the age range 10–102 years. The opposite association between novelty seeking and birth during the half-year containing winter (October–March) as above, is confirmed when comparing those aged upto 25 years to those aged above 25 years. Here, we also find that the temperament scale of harm avoidance among women is significantly associated with the month of birth, with its peak around September for those aged upto 25 years, and around December for those aged above 25 years. The monoamine neurotransmitters are known to be mutually correlated and show complex interactions with each other. It is likely that there is a developmental difference between persons born during different seasons as regards the dynamics of the turnover and interaction among the monoamine neurotransmitters in parallel to the development of the personality traits across the life-span.