Pterygium has a hereditary component, but genetics alone don’t determine whether you’ll develop one. A large nationwide study in Taiwan found that about 22% of the variation in pterygium risk comes from genetics, while roughly 54% comes from individual environmental factors like UV exposure. The remaining 24% traces to shared environmental factors within families, such as living in the same sunny climate or working similar outdoor jobs. So family history matters, but it’s one piece of a larger puzzle.
How Family History Affects Your Risk
If a close relative has pterygium, your chances of developing one are measurably higher. In Taiwan, where researchers tracked the entire national population, the prevalence among people with an affected first-degree relative was 1.64%, compared to 1.34% in the general population. That gap may sound small, but the relative risk numbers tell a more striking story.
Identical twins of the same sex had the highest relative risk, at roughly 15 times the baseline. Siblings of the same sex had about 4.7 times the risk, and children of affected parents had about 3.4 times the risk. Even spouses showed an elevated risk of about 2.1 times, which is important because spouses share environments, not genes. That spousal risk is a reminder that living in the same location and spending time in the same conditions can independently drive pterygium development.
No Single “Pterygium Gene”
Researchers have not identified one gene responsible for pterygium. Several inheritance patterns have been proposed over the years, including a dominant gene with incomplete expression, multiple genes acting together, and more complex multifactorial models. None of these has been definitively confirmed. The condition appears to involve many genes interacting with environmental triggers rather than following a straightforward inherited pattern like, say, eye color.
One area of active interest is how UV light damages the eye’s surface cells at the genetic level. Ultraviolet radiation creates reactive oxygen species that damage DNA and switch on genes involved in tissue remodeling. For years, scientists believed that mutations in p53, a gene that normally tells damaged cells to self-destruct, were the primary driver. Some studies did find elevated p53 protein in pterygium tissue. But other studies found no p53 mutations at all, and later work showed that UV light can raise p53 levels through normal protective mechanisms without any mutation being present. The exact genetic trigger remains unclear.
Epigenetic Changes in Pterygium Tissue
Beyond inherited DNA, pterygium involves epigenetic changes, which are chemical modifications that affect how genes are read without altering the DNA sequence itself. In pterygium tissue, researchers have found that certain gene promoters are silenced through a process called methylation. A recent study identified genome-wide increases in a specific silencing mark (a chemical tag on histone proteins) in pterygium-affected tissue, with 97 genes being improperly shut down. Six of those genes are closely linked to biomarkers for other human diseases, suggesting they may play a causal role in pterygium formation.
These epigenetic shifts likely result from chronic UV exposure rather than being inherited directly. They help explain why pterygium tissue behaves abnormally: its cells are more proliferative than normal conjunctival cells, resist normal cell death signals, and invade the cornea in ways that resemble, at a cellular level, benign tumor growth.
UV Exposure Is the Dominant Trigger
Even with a genetic predisposition, UV radiation remains the strongest environmental driver of pterygium. A meta-analysis of 20 studies covering more than 900,000 people found a global pooled prevalence of about 10.2%. Outdoor workers had 1.76 times the odds of developing pterygium compared to indoor workers. Rural populations had roughly double the prevalence of urban populations (13.2% vs. 6.3%), consistent with greater sun exposure. Men, who are more likely to work outdoors in many of the studied populations, had a higher pooled prevalence than women (14.5% vs. 13.6%).
Age also plays a clear role. Prevalence climbs steadily from about 11% in people aged 40 to 49, to 15.6% in the 50 to 59 group, and 20% by the 60s. This reflects cumulative UV damage over a lifetime rather than a genetic switch flipping at a certain age.
The practical takeaway from the research is that heredity may set the stage by making the eye’s surface tissue more reactive to environmental stress, but UV light is what actually drives the chronic inflammation and tissue growth that become a pterygium. Researchers have described it as genetics loading the gun and sunlight pulling the trigger.
What This Means if It Runs in Your Family
If your parent or sibling has pterygium, you carry a roughly three to five times higher risk than someone without that family history. That’s significant enough to take UV protection seriously: wraparound sunglasses that block UVA and UVB, wide-brimmed hats, and limiting prolonged direct sun exposure, especially during peak hours. These steps matter for everyone but carry extra weight for people with a family history.
There’s also emerging evidence that genetic factors may influence how aggressively a pterygium behaves after surgical removal. One study found distinct gene expression profiles in pterygium tissue that recurred versus tissue that did not. Recurrent cases showed higher activity of genes involved in cell motility and reduced cell adhesion, traits that make tissue more likely to regrow. While genetic testing for pterygium recurrence isn’t standard practice, this research suggests that some people’s biology makes them more prone to regrowth, which could eventually help guide treatment decisions.
The bottom line: pterygium is not purely hereditary, but family history is a real and measurable risk factor. Genetics account for roughly a fifth of the overall risk, with individual UV exposure accounting for more than half. If pterygium runs in your family, the most effective thing you can do is protect your eyes from the sun consistently over your lifetime.