Individuals with autism with intellectual disabilities (ID) are increasingly undergoing genetic testing, posing questions of how parents view/respond to such results. Twenty-eight parents whose offspring had received genetic diagnoses of de novo pathogenic variants associated with autism were interviewed. Genetic diagnoses parents receive concerning their offspring's autism/intellectual disabilities can be 'double-edged' in several ways, having advantages, but also certain disadvantages and limitations. Benefits were medical/scientific (e.g., ending diagnostic odysseys and potentially contributing to research), emotional (e.g., relief, peace of mind and less self-blame), cognitive, social (e.g., validation and confirmation with others - it's 'not just in our head') and financial (e.g., estate planning), now and in the future (e.g., preparing for possible future symptoms, development and availability of treatment and setting realistic expectations). Limitations included a lack of medical treatments related to the genetic diagnosis, a sense of finality and heightened uncertainties which can increase anxieties (e.g., concerning additional symptoms associated with genetic diagnoses and offspring's ability to live independently in the future). Overall, parents were glad to receive the results, seeing the pros outweighing the cons. Parents responded to these tensions in various ways, having mixed feelings, recognizing the trade-offs and/or focusing on their offspring's present needs. Factors such as age of offspring at receipt of genetic diagnosis, parent's scientific background and prior views and degrees of self-blame affected these responses. These data, the first to examine how parents perceive genetic diagnoses received for offspring with autism and ID through whole exome/whole genome sequencing, highlight practical medical and psychological benefits as well as limitations. These findings thus have important implications for future education, engagement of families and research. Providers should be aware of these issues, to inform and assist families, who are considering such testing, about these potential pros and cons and responses.