Both Parents Contribute

Autism is not carried by a single gene from one parent. Hundreds of genes have been associated with autism risk, and both parents contribute genetic variations that influence whether a child develops autism. The genetics of autism are complex, involving common variants, rare mutations, and spontaneous (de novo) changes that occur during conception.

Inheritance Patterns

Autism does not follow a simple inheritance pattern like eye color. Most cases involve the combined effect of many common genetic variants, each contributing a small amount of risk. Some cases involve rare mutations with larger effects. De novo mutations, which are new in the child and not inherited from either parent, account for a meaningful portion of cases, particularly in families with no autism history.

Parental Age

Both maternal and paternal age are associated with increased autism risk, with paternal age showing a slightly stronger association. Older fathers have more de novo mutations in their sperm, which may explain part of this relationship. However, parental age is just one of many factors, and most children born to older parents do not develop autism.

Genetic Testing

Chromosomal microarray analysis and whole exome sequencing can identify genetic factors in some autistic individuals. These tests find a specific genetic cause in about 15 to 40 percent of cases. Results can inform medical management and help families understand recurrence risk. However, a negative genetic test does not rule out a genetic contribution, as many relevant variants remain unidentified.

What This Means for Families

Knowing that autism has a strong genetic basis helps families understand that nothing they did caused their child’s autism. Genetic counseling can provide personalized information about recurrence risk for future pregnancies. Regardless of genetic factors, early intervention through ABA therapy produces meaningful improvements. Treetop ABA Therapy supports families throughout the diagnostic and treatment journey.