Advancing paternal age and simplex autism.

Puleo et al. (2012) looked at the families with one child who has autism. They asked a simple question: does dad's age at birth change autism odds for boys versus girls?

They focused on 'simplex' families—only one child with autism. This matters because these cases often come from new genetic changes, not inherited ones.

Older dads raised autism risk only for daughters. Each extra ten years of paternal age doubled the odds for girls.

For boys, dad's age barely moved the needle. The link was almost flat.

Day-Watkins et al. (2014) extends this picture. They showed that fathers who carry broad autism traits have kids with more severe autism scores across the board. Together, the two papers say: check both dad's age and his personality style when you assess risk.

Antaki et al. (2008) found that girls with autism play in more 'boy-typical' ways. Morrow's team adds a possible reason—girls may need a strong genetic hit, like a new mutation from an older father, to show the autism phenotype.

Kumazaki et al. (2018) spotted estrogen-receptor gene variants that shape social and emotional severity only in some kids. All three studies—paternal age, play style, estrogen genes—point to sex-specific biology under the hood of autism.

When you meet a family with an autistic daughter and an older father, think 'de novo mutation pathway.' This can guide you toward genetic counseling and away from blaming parenting style. For boys, don't over-weigh paternal age; look elsewhere for risk clues. Documenting dad's age and broad autism traits in your intake form takes one minute and sharpens your case picture.