Developing allergies may seem to randomly affect some while others live their lives without even a sniffle to concern themselves with. But it turns out your birthday may have more of an influence on allergy risk than previously known. Researchers from the University of Southampton in England searched strands of DNA to uncover the link between birth season and allergies. Their findings, published in the journal Allergy, have revealed there are long-term effects for what particular season a person is born into.

"We know that season of birth has an effect on people throughout their lives,” said the study’s co-author John Holloway, a professor of allergy and respiratory genetics at the university, in a press release. “Generally, people born in autumn and winter are at increased risk for allergic diseases such as asthma. However, until now, we did not know how the effects can be so long lasting.”

All cell types contain the same DNA. But genetic markers change how certain genes turn on and off, which differentiates them. This phenomenon, known as epigenetics, influences how a particular gene will play a role in the human body, and in this case, for the development of allergic reactions. Researchers scanned through DNA samples from a group of participants who were born on the Isle of Wight in England. They found a pattern in the epigenetic markers among the participants who were born in the same season. Those born in autumn, for example, had an increased risk of developing eczema compared to those born in the springtime. But what researchers found particularly interesting was that these genetic markers affected participants throughout their adult lives — and at least until the age of 18.

"Epigenetic marks are attached onto DNA, and can influence gene expression for years, maybe even into the next generation,” Holloway said. “Our study has linked specific epigenetic marks with season of birth and risk of allergy. However, while these results have clinical implications in mediating against allergy risk, we are not advising altering pregnancy timing."

Allergies are caused when your immune system reacts to a foreign substance, whether it’s something you eat, inhale, inject, or touch, which may be driven by how the season influences a person’s genes. They affect millions of people and some allergen triggers can be severe enough to cause a life-threatening reaction. According to the Asthma and Allergy Foundation of America, thirty percent of adults and 40 percent of children live with allergies. The research team plans on conducting further research to determine why the season you’re born in has an impact on allergy risk. They speculate how differences in temperature, levels of sunlight, health of the mother, and diets play a role.

"It might sound like a horoscope by the seasons, but now we have scientific evidence for how that horoscope could work,” said the study’s lead author Dr. Gabrielle Lockett, a postdoctoral researcher at the University of Southampton, in a statement. “Because season of birth influences so many things, the epigenetic marks discovered in this study could also potentially be the mechanism for other seasonally influenced diseases and traits too, not just allergy."

Source: Lockett GA, Holloway JW, and Soto-Ramirez N, et al. Association of Season of Birth with DNA Methylation and Allergic Disease. Allergy. 2016.