The present study is the first, to our knowledge, to make use of an integrative developmental model to examine, for youth low vs high in internalizing problems: (i) prospective interrelationships between environmental risk exposure (prenatal, postnatal) and OXTR methylation (birth, age 7, age 9); and (ii) the unique contribution of these factors to CU (age 13). Such a model not only has the capacity to further our understanding of how CU develop, but is also important for identifying the timing and targets of intervention to prevent the emergence of CU. We focussed specifically on youth following an early-onset, persistent trajectory of conduct problems, as these typically present with the highest CU levels (14, 15). Based on previous literature, we expected that youth with low vs high internalizing problems would show similar levels of CU, but that youth with low internalizing problems would experience less environmental risk. In order to clarify aetiological pathways to CU, we then tested whether associations between OXTR methylation, environmental risk and CU differed for youth with low vs high internalizing problems.
