First, the article does not assess socioeconomic status as a confounder. Data shows that this makes a difference in non-religious circumcision choice. It did not control for parentla age. Another risk factor.
Second, what factors lead to an autism diagnosis in Denmark? Could there be a double SES selection bias?
Third. This study was of "KKGV20" ritual circumcision performed in private clinics and billed ot the government. Really?
Research published today by the Journal of the Royal Society of Medicine suggests that circumcised boys are more likely than intact boys to develop autism spectrum disorder (ASD) before the age of 10. Risk is particularly high for infantile autism before the age of five. The research was carried out in Denmark among a cohort of all children born between 1994 and 2003. During the study over 340,000 boys were followed up to the age of nine between 1994 and 2013 and almost 5,000 cases of ASD were diagnosed. The study showed that regardless of cultural background circumcised boys may run a greater risk of developing ASD. The researchers also made an unexpected observation of an increased risk of hyperactivity disorder among circumcised boys in non-Muslim families.