First of all, although the most accurate approach is to consider the cause of autism separately for each case, in general, the causes of autism are grouped into three main groups. 1. Environmental factors 2. Genetic factors 3. Epigenetic factors. All three factors intertwine with each other. For example, while environmental factors can affect genetic factors (the ability of genes to express themselves/suppression of expression), at the same time they can cause epigenetic changes to be triggered. Genetic factors, together with other factors, can accompany this condition at a rate of 10% in total. Pure genetic etiology is seen much less frequently. Although many factors related to birth (becoming a father at an advanced age, febrile diseases during pregnancy, especially having had an intrauterine infection, premature birth, prolonged oxygen deprivation of the baby’s brain at birth, cesarean section, formula feeding, etc.) have been reported among environmental factors, there is no definitive evidence that each of these factors alone can trigger and initiate autism. However, heavy metals, exposure to chemical toxic agents in high doses, and for a long time, diet and nutritional disorders are more important factors. Studies have shown that “maternal immune activation”, triggered by disorders in the maternal intestinal microbiota during the pre-pregnancy and pregnancy periods, in other words, the activation of the mother’s immune system against the fetus in the womb, plays a primary role in the development of autism in the development of nerve stem cells into nerve cells during the intrauterine period. Every disorder has medically explainable causes. Nothing happens spontaneously or by chance.