Purpose
The purpose of this paper is to report on the findings from a study commissioned by the Office of the Children’s Commissioner (OCC) in England, concerning intrafamilial child sexual abuse (IFCSA)/incest. Specifically, it aims to explore what is known about the prevalence, nature, and impact of IFCSA and where the gaps in knowledge lie.

Design/methodology/approach
A rapid evidence assessment (REA) was used, the function of which is to: search the literature as comprehensively as possible within given time constraints; collate descriptive outlines of the available evidence on a topic and critically appraise it; sift out studies of poor quality; and provide an overview of the evidence. Over 57,000 documents were scanned, and 296 ultimately systematically analysed.

Findings
It was found that: there is wide variation in prevalence rates between studies; girls are more likely to be victims than boys; the onset of abuse is typically school age; abuse in minority groups is under-reported; sibling abuse may be more common than that by fathers; female perpetrated abuse may be under-reported; families where abuse occurs are often dysfunctional; and IFCSA has significant adverse effects on victims.

Research limitations/implications
A REA is not a full systematic review, differing in the scope and depth of the searches and depending almost exclusively on electronic databases, not accompanied by searching journals by hand.

Practical implications
This work found numerous gaps in current knowledge about IFCSA, which the authors recommend be addressed by further research, including: the scale and nature of IFCSA in disabled victims, research on BME children’s experiences; the prevalence of abuse by stepfathers as compared to biological fathers; the experiences of male victims; the experiences of lesbian, gay, bisexual, and transgendered child victims; the short-term impact of IFCSA based on child victims’ experiences; and more widely, further research on the prevalence of abuse in clinical populations and the relationship between that and prevalence in wider society. In addition to such questions, the OCC inquiry will also investigate issues surrounding child protection and criminal justice responses to (IF)CSA and how these might be improved. The evidence base for this section of the inquiry is reported in Gekoski et al. (2016).
Originality/value
The findings of this research provide the evidence base for a new two-year inquiry into the subject of IFCSA by the OCC.