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Is Autism Genetic?

Episode 75, Experience Miracles Podcast | Host: Dr. Tony Ebel, DC, CACCP, Pediatric Chiropractor & Founder of PX Docs | Published: February 4, 2024 | Duration: ~62 min Guest: Greer McGuinness, RD, Certified Detox Specialist, Master Herbalist, Founder, Biomedical Healing for Kids

Key Takeaways

• Autism is not solely genetic. Greer McGuinness, a registered dietitian, certified detox specialist, and master herbalist, explains that epigenetics shows how environmental triggers activate or suppress genetic predispositions. Genetics load the gun; environment pulls the trigger.
• Approximately 80% of children with autism present with a nervous system stuck in Sympathetic Dominance (chronic fight-or-flight), according to Greer’s clinical experience. Addressing nervous system dysregulation is a foundational step in the healing process.
• Greer’s son Keegan regressed into autism at 19 months. After genetic testing came back normal at age 3.5, it confirmed what she had suspected: the root cause was environmental and physiological, not predetermined genetic coding.
• The MTHFR gene variant is one example of how genetics and environment interact, carrying the variant doesn’t cause problems by itself, but combined with toxic environmental exposure, poor gut health, and nutritional deficiencies, it can contribute significantly to chronic illness in children.
• Individualized care is critical. When providers hand parents cookie-cutter protocols, they miss the child’s unique combination of genetic susceptibilities, birth history, gut status, and nervous system state, the very factors that determine which interventions will work.

Why Autism Isn’t “Just Genetic”, and What That Means for Healing

Autism is not a static genetic sentence. The science of epigenetics shows that genes are not simply “on” or “off” from birth, they are continuously influenced by environment, nutrition, gut health, toxin exposure, and nervous system state. Greer McGuinness, who holds a master’s degree in nutritional health with a focus on epidemiology, explains it this way: we all carry roughly 27,000 genes, but which of those genes express into symptoms depends heavily on what surrounds them.

The phrase “genetics load the gun, environment pulls the trigger” captures the mechanism. A child can carry the MTHFR gene variant, which affects methylation, detoxification, and B12/folate processing, and never develop chronic illness, as long as the environment, diet, and nervous system remain supportive. A second child with identical genetics, placed in a more toxic environment with poor gut health and higher physiological stress, can develop serious chronic symptoms. Same code, completely different outcome.

For parents of children with autism, ADHD, sensory processing issues, or other chronic conditions, this is meaningful news. It means the diagnosis is not the destination. It means the body retains the ability to heal, adapt, and reorganize, especially when the foundational stressors driving nervous system dysregulation are addressed. Greer’s son Keegan is living proof: after years of biomedical and nervous system-focused interventions, the rigidity, sensory hypersensitivity, and sympathetic dominance that once defined his daily experience began to release.

From Wrestler to Registered Dietitian: How Greer McGuinness Came to Biomedical Healing [00:06:00 – 00:13:00]

Greer McGuinness: My career path started unexpectedly. I was on my way to the Olympics as a wrestler, female wrestling was brand new and up-and-coming at that time. I got injured within three months of college and that career was over. My sister, a social worker at a hospital, suggested dietetics. I had no idea what it was. But it fit.

Going through conventional training, I thought I was learning the correct way of doing things. I thought everyone else was misinformed. Dietitians take the same undergraduate courses as doctors and nurses, and now a master’s degree is required. I have a master’s in nutritional health with a focus on epidemiology. At the time, I believed in the Western medicine model completely.

Dr. Tony Ebel: Conventional dietitian training is super medical, right?

Greer McGuinness: Exactly. Which is why what happened with my son hit so hard. During my pregnancy, I had severe hyperemesis, I couldn’t start my morning without throwing up. I also developed PUPPS: a pregnancy rash that covers the body when the mother’s and baby’s DNA don’t mesh well. It was on 90 percent of my body. Nothing worked. I wasn’t sleeping. I was miserable.

My son was born a day shy of 39 weeks. I believe the stress on my body from the PUPPS is part of why my water broke early. He was five pounds, nine ounces, perfect Apgar score, no apparent issues. But the birthing experience itself was traumatic: three hours of pushing, cord wrapped around his neck.

Dr. Tony Ebel: What about latch and early regulation in those first weeks?

Greer McGuinness: He couldn’t latch correctly. He was small, and we wound up back in the hospital for dehydration. I pumped and bottle-fed, but every time my let-down reflex triggered, the PUPPS rash would return across my whole body. Eventually I had to stop breastfeeding, which came with significant mom guilt.

What I know now, and didn’t know then, is that breastfeeding isn’t just about nutrition. There’s a co-regulation that happens between mother and infant, a physical nervous system connection. When that’s disrupted, even in the first days of life, it can leave a baby’s nervous system more sensitive from the start. Hindsight is 20/20.

“There’s something different when you’ve gone through it as a parent and you do the job as a provider. There’s a level of compassion, a level of relatability, a level of knowing what the real cheat codes are to healing that you don’t get in books or curriculums.”, Dr. Tony Ebel

Regression at 19 Months and the Genetic Testing Turning Point [00:19:00 – 00:31:00]

Greer McGuinness: Keegan developed normally, then regressed at 19 months. He went from talking, smiling, pointing, and making eye contact to looking straight through me and not saying a single word. He walked through the house every day like a zombie. I had videos of him talking. I knew something had changed.

Every practitioner I saw, early intervention therapists, his pediatrician, the developmental pediatrician, told me this was genetic. When I asked the developmental pediatrician to explain why he had regressed, she shrugged and said, “This is just how autism presents now.”

Dr. Tony Ebel: That’s the question I always come back to in those conversations. Will you please explain regressive autism to me if it’s genetic? Was there some internal stopwatch set to 19 months? That’s not how genetics work. It’s wild how much conventional medicine is still beholden to that.

Greer McGuinness: I started questioning it, but everyone told me to take myself out of the equation, that I was too close as a mom. I regret listening to them. I should have trusted my instincts. Mom gut does not steer you wrong.

When Keegan was about three and a half, we went to a geneticist and did full gene mapping, they took about 20 vials of blood. The assistant called back and said, “Everything came back normal. You can follow up with your developmental pediatrician.” I hung up the phone and just sat there. Everything I had been told about autism being genetic suddenly made zero sense.

I asked the geneticist to also test for MTHFR. She turned and said, “What’s the point? He has autism, so what’s the point?” That response told me everything. They weren’t curious. They weren’t looking for what could be done. They were done.

That normal genetic panel was the turning point. It confirmed: the cause wasn’t predetermined code. Something happened. Something environmental, something physiological. And if something happened, something could be done.

“Mom gut does not steer you wrong. I regret listening to people who told me to take myself out of the equation. I should have trusted it from the beginning.”, Greer McGuinness

What Epigenetics Actually Means for Children with Autism [00:39:00 – 00:47:00]

Dr. Tony Ebel: When parents come out of the purely genetic narrative, they open up to epigenetics. What do parents need to understand about epigenetics, both to make sense of how the challenges developed and to know that healing is actually possible?

Greer McGuinness: We all have about 27,000 genes, pulling half from each parent. Genetics is still a fascinating and early-stage field, we’re still connecting the dots. Most families in this community have heard of MTHFR, which affects detoxification and B12/folate metabolism. It’s a significant genetic factor.

But here’s the key: if two children both carry the same genetic variants, and one grows up in a toxic, high-stress environment with poor nutrition and the other grows up in a clean, low-stress environment with good food and good care, the outcomes will be completely different. That’s why we say genetics loads the gun and environment pulls the trigger.

Carrying a variant doesn’t doom a child. Keegan carries one of the celiac genetic markers, he’s 95 percent likely to develop celiac disease at some point if untreated. So he’s on a gluten-free diet now to prevent that from happening. Does he have celiac right now? No. But we have the information to act on it.

Dr. Tony Ebel: That’s the power of this. You learn how things go sideways, and then you flip it. You now know what creates susceptibility, which means you know what creates resiliency. If that causes inflammation, the opposite creates anti-inflammatory effects. Understanding epigenetics isn’t scary. It’s empowering.

My first mentor, Dr. Cody, had a story that cemented this for me. He adopted one of a pair of identical twins. His twin was raised in his home: adjusted from birth, organic diet, no vaccines, minimal stress, faith-based household. The other twin went to a highly toxic environment, medically dependent, chronic illness, juvenile diabetes, juvenile arthritis, sensory spectrum issues.

Same genetics. John, raised in Dr. Cody’s home, graduated college and went into the Army. The other twin never made it through a standard education. Same code, completely different story.

“By studying chronic illness and autism, you learn what creates susceptibility, and that’s actually the good news. Because the opposite of what creates sickness creates health. The opposite of susceptibility creates resiliency.”, Dr. Tony Ebel

Nervous System Regulation: The Missing Piece in 80% of Cases [00:47:00 – 00:55:00]

Greer McGuinness: It came up in a surprising way. Keegan mentioned out of nowhere, when he was about seven or eight, that he remembered falling off the bed when he was little. I went to my husband, and it was true. When Keegan was about two, he rolled off the bed. He landed on his arm, not his head. I had forgotten about it, but he hadn’t.

That detail sent me down a path toward understanding nervous system regulation. I started researching the Vagus Nerve, Safe and Sound Protocol, primitive reflexes, vibrating plates, and the Masgutova Method. What I found was an entire world of interventions that addressed the nervous system directly, things I had never encountered in my dietetics training.

Keegan had always been very OCD-rigid, very sympathetically wound up. If you moved him from his usual seat, it was a crisis. Once we started working on the nervous system and primitive reflexes, something shifted. He relaxed. The tension released. He stopped needing things to be so controlled and rigid.

Dr. Tony Ebel: When you’re doing intake now, what percentage of kids do you find right away are stuck in Sympathetic Dominance, hypersensitive, and need that nervous system work?

Greer McGuinness: Probably 80 percent or more.

Dr. Tony Ebel: It’s one of the lead keys. There’s a sequence to getting sick, so there’s a sequence to healing. The nervous system has to be part of the equation. When families come to us having already done solid biomedical and functional work, changed nutrition, removed chemicals, added targeted supplements, and then we unlock the nervous system on top of that, healing accelerates dramatically. The combination is where the real momentum happens.

How to Work With Parents Without Overwhelming Them [00:51:00 – 00:58:00]

Greer McGuinness: I always give families three things to work on when they leave a consultation. Never more than three. Because this world is enormous, I’m still learning, and I’ve been in it for years. The most common response from parents when I give them a supplement protocol is, “I’m feeling overwhelmed.” That’s real. We have to meet them there.

I work on the basis of three components per visit. I give them bite-sized, directed research. I tell them: hold off on the open-ended Google research. I’ll give you exactly the main points to focus on based on your child’s test results. If you want to go down a rabbit hole, I’ll go with you, but it needs to be directed to what’s actually relevant for your kid.

Dr. Tony Ebel: That’s the Pareto principle in practice. Twenty percent of what you do, the basics, done consistently, drives 80 percent of the healing. We’re in a paradox right now where we have access to increasingly fancy interventions. Fancier doesn’t mean better. The basics matter most, especially because healing is sequential.

And when a child hits a plateau, things were moving forward, then they stall, that’s almost always subluxation and nervous system dysregulation underneath it. That’s the cheat code. When you unlock the nervous system in a family that’s already living clean, the healing accelerates fast.

Greer McGuinness: I pose ideas as questions. I had a family recently and I asked, “Have you ever taken your child to a chiropractor?” They said no. I said, “I think your kiddo’s nervous system is really tight.” We talked about it, and it was like a light bulb went off, they started naming symptom after symptom that fit. I said, “You need to find a chiropractor trained by PX Docs.” I’m never positioning myself as an authority over parents. I work for them. I’m an assistant and a helper. And when you approach it that way, they open up.

“Parents are shocked when you actually listen to them. They say, ‘Wait, are you actually hearing me?’ And that’s when the healing starts. Not when the protocol begins. When they finally feel heard.”, Dr. Tony Ebel

How to Connect With Greer McGuinness and Biomedical Healing for Kids [00:59:00 – 01:02:00]

Dr. Tony Ebel: I want to make sure parents know how to find you, because several families I’m working with right now need exactly what you offer, and they can connect with you virtually.

Greer McGuinness: Everything is under “Biomedical Healing for Kids.” That’s my Instagram handle, my website, and my Facebook group. The Facebook group is very active, parents ask questions, tag me in discussions about supplements and test results, and share what’s working. On Instagram, I post regular educational content. I also have a membership launching soon where I walk parents through how to safely and effectively address detox, rebalance the system, and navigate the healing process step by step, especially for families who aren’t local or aren’t sure where to start.

Dr. Tony Ebel: Round two is already booked in spirit. We’re coming back for a full episode on detox, when to do it, when not to, how to do it safely. That is absolutely not a baby step topic. It deserves its own full conversation. Greer, we couldn’t be more grateful for everything you bring to these families.

Frequently Asked Questions

Is autism caused by genetics?

Autism is not solely genetic. While genetic variants, such as MTHFR and celiac markers, can create susceptibility, they do not determine outcomes by themselves. The emerging science of epigenetics shows that environmental factors, gut health, toxin exposure, and nervous system dysregulation interact with genetics to produce symptoms. Regressive autism, where a child develops normally and then loses skills, is difficult to explain through genetics alone, and that disconnect is what led Greer McGuinness, a registered dietitian and certified detox specialist, to pursue biomedical healing after her son Keegan regressed at 19 months.

What is epigenetics and why does it matter for children with autism?

Epigenetics is the study of how environment influences whether genes are expressed or suppressed. Every person carries around 27,000 genes, but which of those become active depends on factors like diet, gut health, toxin exposure, and stress. The phrase used by Greer McGuinness, “genetics load the gun, environment pulls the trigger”, captures the core idea. Two children with identical genetic variants can have entirely different health outcomes based on their environment. For parents of children with autism, this means the diagnosis is not fixed, and targeted interventions can meaningfully shift outcomes.

What does “nervous system stuck in fight-or-flight” mean for a child with autism?

Sympathetic Dominance means the child’s autonomic nervous system is chronically locked in a high-alert, stress-response state rather than the calm, regulated state needed for digestion, sleep, learning, and social connection. Signs include rigidity, hypersensitivity, difficulty with transitions, poor sleep, and gut issues. Greer McGuinness finds this pattern in approximately 80% of children she works with clinically. Addressing nervous system dysregulation, through approaches like neurologically-focused chiropractic care, Safe and Sound Protocol, and primitive reflex work, is often a foundational step before other interventions fully take hold.

How should parents approach information overload when navigating biomedical healing?

Greer McGuinness recommends that practitioners and parents limit new action steps to three per consultation. The biomedical and functional world is enormous, and too much information at once leads to overwhelm and inaction. Greer guides parents toward directed research based on their child’s specific test results, rather than open-ended Google searches that produce anxiety without direction. Dr. Tony Ebel reinforces this with the Pareto principle: roughly 20% of the foundational basics drive 80% of the healing, especially early in the process.

How do I find a chiropractor trained in neurologically-focused pediatric care?

The PX Docs directory connects families with chiropractors trained specifically in Neurologically-Focused Chiropractic Care for children. These practitioners use INSiGHT Scans to assess nervous system function and develop individualized care plans rather than cookie-cutter protocols. Greer McGuinness actively refers her clients to PX Docs-trained chiropractors as a complement to biomedical healing, particularly when children show signs of nervous system dysregulation.

How do I connect with Greer McGuinness for biomedical support?

Greer can be found across all platforms under Biomedical Healing for Kids, her Instagram, website, and Facebook group all share that name. She offers virtual consultations and is launching a membership program focused on safe, step-by-step detox and system rebalancing for families navigating autism and chronic childhood illness. Her Facebook group is an active community where she responds to parent questions about supplements, testing, and protocols.

Resources & Related Content

• Autism & Neurologically-Focused Chiropractic Care, PX Docs overview of autism, root causes, and drug-free approaches
• The Perfect Storm Framework, How prenatal stress, birth trauma, and early toxin exposure combine to affect children’s nervous systems
• Birth Trauma and Nervous System Development, How birth interventions affect the brainstem and upper cervical spine
• Vagus Nerve Dysfunction in Children, Overview of vagus nerve’s role in regulation and how dysfunction develops
• Find a PX Docs Office Near You, PX Docs Directory
• Greer McGuinness, Biomedical Healing for Kids: Instagram | Facebook Group: “Biomedical Healing for Kids”
• Next Episode: Q&A: Why Kids Plateau (or Even Regress) in the Middle of Their Healing Journey