What Causes Specific Learning Disabilities? Genetic and Environmental Factors

When a child struggles persistently with reading, writing, or math despite receiving reasonable instruction and support, the question educators and parents ask first is: why? The answer, for children with Specific Learning Disabilities (SLDs), lies not in classrooms or effort, but deep within neurobiology. SLDs are brain-based disorders rooted in a complex mix of genetic and environmental factors – and understanding these causes is the first step to supporting affected children effectively.

SLDs are neurobiological – not educational – in origin 🔗

Before exploring the specific causes, it is worth establishing one foundational fact: SLDs reflect fundamental differences in how specific neural pathways develop and function. They are not simply the result of poor teaching, limited effort, or insufficient exposure to learning. Brain imaging studies consistently confirm the biological basis of these conditions. The causes can be broadly grouped into three categories: genetic influences, prenatal and perinatal environmental factors, and post-natal environmental factors.

Genetic influences 🔗

Most people recognize that learning disabilities run in families, but they often don’t make the connection that it’s genetic, as researchers at the Yale Program for Learning Disability Research have noted. In fact, children who have a parent with a learning disability are more likely to develop one themselves. This hereditary pattern has been confirmed across decades of research, and scientists have spent the last two decades identifying the specific genes and genetic variants associated with prominent learning disabilities.

Genetic factors are estimated to be the main cause of learning disability in around 50% of all severe cases. The genetic basis of SLDs is broad: it includes chromosomal abnormalities, copy number variants (gains or losses of entire gene copies), single gene disorders, and mitochondrial disorders. Many of the implicated genes play roles in neurogenesis, neuronal migration, and cellular signaling – all processes critical to normal brain development.

What twin and family studies tell us 🔗

Twin studies have been particularly illuminating. Research on twins shows substantial genetic influence on individual differences in learning skills like reading and calculation, and multivariate genetic research has demonstrated that the same set of genes is largely responsible for genetic influence across different cognitive areas. Importantly, not every child with a genetic predisposition will develop an SLD – the risk is probabilistic, not deterministic. A child with a family history of SLD is at higher risk, but many such children develop typically, particularly in enriched and supportive environments.

Specific genes under investigation 🔗

Researchers are actively working to map the specific genetic architecture of SLDs. A study published in Medicina analyzed nine families with multiple members diagnosed with SLD and identified variants in genes including DGKI, DIP2A, KIAA0319, and PCNT – with the variant-carrying parent frequently reporting language difficulties. While the field is still evolving, next-generation sequencing technologies are rapidly expanding what researchers can detect, and scientists hope to eventually use genetic screening to identify at-risk children as early as infancy, enabling early intervention before children fall behind.

Prenatal and perinatal environmental factors 🔗

Genes do not work in isolation. The environment a developing child is exposed to – starting from the womb – can significantly alter neurological development and raise the risk of SLDs. Several prenatal and perinatal factors are well-documented in the research literature.

Maternal alcohol use 🔗

Alcohol consumed during pregnancy crosses the placenta and directly affects fetal brain development. Alcohol use during pregnancy is the leading cause of preventable birth defects, developmental disabilities, and learning disabilities. The resulting conditions, collectively known as Fetal Alcohol Spectrum Disorders (FASDs), include a range of impairments. People with Alcohol-Related Neurodevelopmental Disorder (ARND), one form of FASD, may have intellectual disabilities and problems with behavior and learning, doing poorly in math, memory, attention, and judgment. The National Institute on Alcohol Abuse and Alcoholism is clear: there is no known safe amount of alcohol during pregnancy, and alcohol can disrupt brain development at any stage, even before a woman knows she is pregnant.

Drug use and exposure to toxins 🔗

Exposure to drugs and environmental toxins during pregnancy poses serious risks to the fetal nervous system. Factors that affect a fetus developing in the womb, such as alcohol or drug use, can put a child at higher risk for a learning problem or disability, according to the National Institute of Child Health and Human Development (NICHD). Beyond alcohol, substances like cocaine and certain prescription medications are recognized as neurotoxic to the developing brain.

Anoxia (oxygen deprivation) 🔗

Birth asphyxia – a loss of oxygen around the time of delivery – is another perinatal factor associated with neurological injury and increased risk of learning difficulties. Environmental factors including birth asphyxia and complications of prematurity can cause or contribute to learning disabilities. Even brief periods of oxygen loss during a critical developmental window can disrupt the normal formation of neural circuits.

Maternal malnourishment and illness 🔗

Severe nutritional deficiencies during pregnancy, as well as serious maternal illnesses and infections such as rubella, cytomegalovirus (CMV), and toxoplasmosis, are also associated with increased risk of neurodevelopmental problems in the child. The brain is an extraordinarily metabolically active organ during fetal development, and disruptions to the maternal environment – whether nutritional or infectious – can leave lasting imprints.

Post-natal environmental factors 🔗

The risk window does not close at birth. A child’s brain continues to develop rapidly through early childhood, making it vulnerable to a range of post-natal environmental hazards as well.

Lead exposure 🔗

Lead is one of the most extensively researched environmental neurotoxins. Lead exposure targets fetal and infant neural stem cells and has detrimental effects on developing neural and glial cells, adversely influencing cognition and behavior – and there is no known safe threshold of lead exposure for children. Children can be exposed to lead through old paint in homes, contaminated soil, water from lead pipes, and industrial emissions. Research from the Icahn School of Medicine at Mount Sinai demonstrates that even low-level lead exposure can undermine key cognitive functions in young children, with memory and attention – both foundational for academic success – being particularly affected.

Head injuries and brain damage 🔗

Accidents resulting in traumatic brain injury (TBI) during infancy or early childhood can damage specific regions of the brain responsible for language processing, reading, and mathematical reasoning. Depending on the location and severity of the injury, a child who was previously developing typically may begin to show characteristics consistent with an SLD. This highlights an important point: SLDs can be acquired, not only inherited or present from birth.

Radiation and environmental emissions 🔗

Prolonged or significant exposure to radiation and certain airborne emissions during early childhood has also been flagged in the research literature as a potential contributor to neurological deficits. While this is an area that requires further investigation, it is consistent with the broader understanding that the developing brain is particularly sensitive to environmental insults during the early years of life.

What does not cause SLDs – and why this matters 🔗

This is a critical distinction that is frequently misunderstood, and getting it wrong has real consequences for children. The DSM-5 explicitly requires that inadequate educational opportunity must be ruled out before a diagnosis of SLD can be confirmed. That is because inadequate instruction can mimic the academic profile of an SLD – but it is not the same thing, and it does not cause the underlying neurological condition.

Dyslexia, for instance, is not primarily the result of a lack of appropriate instruction, cultural factors, environmental or economic disadvantage, or limited English proficiency. An SLD cannot be explained by factors such as inadequate educational methods, adverse psychosocial circumstances, or cultural differences. These are exclusionary factors – their presence must be investigated and ruled out during diagnosis.

However – and this is equally important – while poor instruction does not cause an SLD, it absolutely worsens outcomes for a child who already has one. A child with dyslexia who attends a school with evidence-based reading instruction will fare far better than one who does not. The absence of quality instruction does not create the neurological difference, but it denies the child the scaffolding needed to navigate it. This is why early identification, combined with appropriate, targeted support, is so critical.

The interplay between genes and environment 🔗

It is rarely a single cause in isolation. Research increasingly points to a gene-environment interaction model – where genetic vulnerabilities may be activated or amplified by environmental stressors. A poor home learning environment or significant psychosocial stressors may trigger the expression of genes that would otherwise not manifest as learning difficulties in more supportive conditions. Conversely, enriched environments and early intervention can buffer against genetic risk. The science of epigenetics – how environmental factors alter gene expression without changing the DNA sequence – adds yet another layer of complexity to this picture, and is an active area of SLD research.

Understanding that SLDs arise from a combination of neurobiological, genetic, and environmental factors fundamentally shifts how educators, parents, and clinicians should respond. It moves the conversation away from blame – of the child, the teacher, or the family – and toward evidence-informed support. A child with an SLD is not struggling because they aren’t trying hard enough. They are navigating a world built for a brain wired differently from theirs, often without the tools they need to do so.

What do you think? If genetic screening for SLD risk could be offered to newborns, what opportunities and challenges might that create for early intervention in schools? And how should educators balance the role of quality instruction knowing that poor teaching, while not a cause of SLDs, can significantly worsen the outcomes for children who have them?

References

1. https://ncld.org/understand-the-issues/specific-learning-disabilities/
2. https://pressbooks.usnh.edu/understandingandsupportinglearnerswithdisabilities/chapter/specific-learning-disability/
3. https://medicine.yale.edu/news/yale-medicine-magazine/article/uncovering-the-genetics-of-learning-disabilities/
4. https://www.nichd.nih.gov/health/topics/learning/conditioninfo/causes
5. https://www.sciencedirect.com/science/article/abs/pii/S175172221500116X
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC4091916/
7. https://www.mdpi.com/1648-9144/59/8/1503
8. https://my.clevelandclinic.org/health/diseases/15677-fetal-alcohol-syndrome
9. https://www.cdc.gov/fasd/about/index.html
10. https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/understanding-fetal-alcohol-spectrum-disorders
11. https://journals.sagepub.com/doi/10.1177/09603271241285523
12. https://www.mountsinai.org/about/newsroom/2025/prenatal-and-childhood-lead-exposure-linked-to-faster-memory-decay-in-children
13. https://dyslexiaida.org/dsm-5-changes-in-diagnostic-criteria-for-specific-learning-disabilities-sld1-what-are-the-implications/
14. https://portal.ct.gov/sde/special-education/specific-learning-disability-and-sld—dyslexia
15. https://pmc.ncbi.nlm.nih.gov/articles/PMC10453094/
16. https://pmc.ncbi.nlm.nih.gov/articles/PMC6251766/