Genetics Are Primary

Autism is predominantly genetic. Twin studies show heritability of 60-90%, meaning genetics account for the majority of autism risk. Hundreds of genes have been implicated, with both common variants (each contributing small risk) and rare mutations (with larger individual effects) playing roles. De novo mutations, new in the child and not inherited, account for some cases, particularly in families with no autism history.

Brain Development

Autism involves differences in brain development that begin prenatally. Neuroimaging studies show atypical connectivity patterns, differences in cortical thickness, and altered development of areas involved in social processing, sensory integration, and executive function. These differences are established during pregnancy, making autism a condition of brain development rather than something that happens after birth.

Environmental Factors

While genetics dominate, environmental factors interact with genetic predisposition. The most consistent environmental associations include advanced parental age, extremely premature birth, very low birth weight, and certain prenatal complications. These factors are modest in effect and do not independently cause autism; they likely interact with existing genetic vulnerability.

What Does NOT Cause Autism

Vaccines do not cause autism (confirmed by studies of millions of children). Parenting style does not cause autism. Diet, screen time, and common household products have not been shown to cause autism. The discredited “refrigerator mother” theory from the 1960s caused enormous harm and has been thoroughly debunked.

The Bottom Line

Autism results from complex interactions between genetic predisposition and prenatal environmental factors. There is no single cause and no way to prevent it. What families can control is how they respond: early identification and evidence-based intervention produce the best outcomes. Treetop ABA Therapy provides comprehensive services that help every child reach their potential.