Previous research about intrafamilial child sexual abuse was not able to identify specific risk factors that distinguish this unique subgroup from other sexual offending subgroups. In comparison to other groups of sexual offenders, men convicted of intrafamilial sexual child abuse (ICSA) are found to exhibit more similarities to non-offending fathers than extrafamilial sexual offenders. Consequently, the risk assessment of sexual recidivism among “incest offenders” lacks evidence-based evaluation criteria. Given the suggestion that family system factors should be included in research on the onset of ICSA, we employed the Vulnerability to Incest Model proposed by Trepper and Barrett (1989, https://doi.org/10.4324/9780203776605) in a qualitative single-case analysis. A comparative analysis of ten court evaluations of ICSA offenders revealed that all families in which ICSA has occurred demonstrated at least two vulnerability factors. The analyzed offenders exhibited comparable patterns of masculine sexual entitlement. The utility of this recently developed construct for sexual violence research is discussed and implications for further research proposed.