Neurodevelopmental disorders are a heterogeneous group of clinical conditions characterized by deficits in one or more aspects of development, with the most prevalent subgroups being autism spectrum disorders and intellectual developmental disorders. Longitudinal studies have shown a significant increase in the number of children with autism spectrum disorders over the past few decades compared to the stable prevalence of intellectual developmental disorders. The aim of this study was to examine and compare the attitudes of parents of children with autism spectrum disorders and parents of children with intellectual developmental disorders regarding genetics, vaccination, and stress as causes of these disorders. The sample consisted of 80 parents, with 40 parents of children with intellectual developmental disorders and 40 parents of children with autism spectrum disorders. The study used a survey as the instrument, employing content analysis, interviewing, and scaling techniques. Data were statistically analyzed using quantitative methods in the JASP program. The results showed that parents' attitudes towards genetics as a cause did not statistically differ, with the most of parents not considering genetics as a cause of neurodevelopmental disorders (40%). There was a notable difference between these two subgroups of neurodevelopmental disorders in the number of children who had undergone genetic testing. A third of the participants expressed a negative attitude towards genetic testing in the future. A statistically significant difference was confirmed in attitudes towards vaccination as a cause of disorders. While most parents did not believe that stress caused their child's disorder, a higher number of parents with children who have intellectual developmental disorders cited stress as a contributing factor. Well-informed parents about the origins of neurodevelopmental disorders influence the lives of entire families, reducing the risk of unnecessary exposure of children to various interventions and treatments.