Refugee children that have experienced traumatic situations are at increased risk of developing psychological disturbances. While some refugee children develop emotional and behavioural disorders (post-traumatic stress disorder, anxiety, or depression, for example), others exhibit remarkable resilience. This variability is linked to the complex interplay between individual traits, such as genetic factors, and characteristics of the environment. The EU-funded CARINGTrauma project developed an innovative statistical approach to explore the complex and interactive causal relations between the various determinants of mental health across multiple domains. It used a unique dataset from a large study of Syrian refugee children and their caregivers (BIOPATH). The data analyzed included demographic, genetic, social, psychological, and environmental variables, allowing a comprehensive evaluation of the causal determinants of mental health of refugee children. We found that daily stressors are important determinants of refugee children's mental health and that the level of exposure to war events, violence re-victimization and caregiver mental health are particularly relevant causal determinants for severe and persistent psychological problems.