IMPRS DOCTORAL DEFENCE: Fenja Schlag

Abstract

Mastering social skills in childhood and adolescence is essential for healthy development and later-life well-being, yet social functioning varies across development, contexts, and individuals. In her thesis, Fenja applied modern genetic epidemiological methods to investigate the genetic architecture of social behaviour, and genetic links with cognition, language, life-span outcomes, and neurodevelopmental conditions. In her empirical analyses, Fenja demonstrated that social behaviour is genetically largely independent from cognitive and language abilities, with strong gene-environment correlations present within each domain. Large-scale genome-wide meta-analyses identified two genetic variants associated with peer problems and showed that low prosocial behaviour and peer problems represent largely distinct genetic dimensions. Polygenic analyses further revealed trait-, age-, and context-specific genetic links between social behaviour and neurodevelopmental conditions, with both shared and condition-specific patterns. Overall, the findings highlight the multidimensional and context-dependent genetic nature of social behaviour and underscore the importance of environmental influences in its development.