What Causes an Autism Spectrum Diagnosis?
Autism spectrum diagnoses are now known to be largely genetic in origin, and runs in families. Twin studies have uncovered many examples of identical (monozygotic) twins having autism spectrum diagnoses. One may have autism and the other AS, but when one identical twin is autistic, the other one is as well. If autistic conditions were not genetic, this would probably not happen. Studies of fraternal twins (dizygotic) have shown that when one twin has an autism spectrum diagnosis, the other one usually does not. If autism were caused by conditions in the mother’s womb, this would not occur. The rate of autism spectrum diagnoses in fraternal twins is the same as the rate in siblings. Since the severity of the autistic condition may vary in identical twins, this tells us that there is some environmental influence, but scientists don’t know yet what it is. Psychological theories abound. One of the major ones is called Theory of Mind (TOM). This holds that autistic people have an impaired a
