Do twins of older parents show different genetic markers for autism?

PostedNovember 19, 2025

UpdatedNovember 19, 2025

ByMy Patient Advice

Author: Lucia Alvarez, MSc | Reviewed by: Dr. Rebecca Fernandez, MBBS

Yes, research suggests that in older parent twins, especially those born to fathers and mothers of advanced age, distinct genetic and epigenetic markers related to autism may be present. Parental age is already a recognised factor in autism risk, and when twins are born to older parents, the chances of spontaneous genetic mutations or altered gene expression may be higher.

In twin studies, comparing those born to older versus younger parents reveals differences in both DNA sequences and epigenetic patterns, such as DNA methylation. These changes can influence how genes function during early development, potentially increasing susceptibility to autism traits in one or both twins.

Why Parental Age Affects Twin Genetics

Here are two keyways in which older parent twins may show different autism-related genetic features:

Increased de novo mutations in older fathers

As paternal age rises, so does the likelihood of spontaneous genetic mutations passed to offspring. In twin studies, these mutations may appear in only one twin or affect both, contributing to variations in autism traits and developmental outcomes.

Age-related changes in epigenetic regulation

Older parental age has also been linked to changes in epigenetic markers, including those that regulate brain development. These changes may affect how autism-associated genes are expressed in twins, even when their DNA is nearly identical.

Understanding how older parent twins may carry unique autism-related markers can provide valuable guidance for early screening and personalised support. Visit providers like Autism Detect for personal consultations and further guidance on screening and support.

For a deeper dive into the science, diagnosis and full treatment landscape, read our complete guide to Genetic Influences.

Lucia Alvarez, MSc

Author

Lucia Alvarez is a clinical psychologist with a Master’s in Clinical Psychology and extensive experience providing evidence-based therapy and psychological assessment to children, adolescents, and adults. Skilled in CBT, DBT, and other therapeutic interventions, she has worked in hospital, community, and residential care settings. Her expertise includes grief counseling, anxiety management, and resilience-building, with a strong focus on creating safe, supportive environments to improve mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy.

Dr. Rebecca Fernandez, MBBS

Reviewer

Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewer's privacy.