Maladaptive personality traits and romantic relationship Satisfaction: A monozygotic co-twin control analysis

The recent inclusion of an alternative model for personality disorders in the Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5; American Psychiatric Association, 2013a) highlights the importance of extreme variants of personality for psychopathology. The maladaptive personality traits described in the alternative model comprise 5 higher-order domains and 25 lower-order facets that capture pathological levels of personality. The present report adds to a growing body of research on the implications of maladaptive personality traits for functioning by demonstrating significant associations between each of the higher-order domains (Negative Affect, Detachment, Antagonism, Disinhibition, and Psychoticism) and most of the lower-order facets and lower romantic relationship satisfaction in a population-based sample of 284 monozygotic (MZ) adult twins. We further capitalized upon co-twin differences in levels of personality pathology in a causally informative approach, the MZ co-twin control study design. Co-twin control analyses indicated that higher levels of Negative Affect, Detachment, Disinhibition, and Psychoticism, as well as several lower-order facets, were associated with lower romantic relationship satisfaction even after accounting for the genetic and environmental factors shared by twins that confer liability toward personality pathology and psychosocial dysfunction. The present results lend support to the potentially causal implications of personality pathology for interpersonal functioning, even in a community sample unlikely to be evidencing clinical levels of pathology, by suggesting that extreme variants of personality, manifested by comparably extreme deviations in thinking, feeling, behaving, and interacting with others, may lead to impaired functioning in important domains.