The Big Five traits are known to have a significant degree of heritability ("openness to experience was estimated to have a 57% genetic influence, extraversion 54%, conscientiousness 49%, neuroticism 48%, and agreeableness 42%", according to the wiki article on the Big Five): I have no reason to doubt that this is not also true of Socionics personality traits - the discrepancy may be down to a lack of available data to make an adequate study, or because each type is a very specific thing rather than something more general such as "extraversion" etc.