Polycystic ovary syndrome (PCOS) does not have one single cause. According to the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), researchers believe it develops from a combination of genetics, hormone imbalances, and metabolic factors working together, rather than any one trigger on its own.
That combination is part of why PCOS looks so different from woman to woman. Some deal mainly with irregular periods. Others deal mainly with weight and blood sugar issues. Both groups may be dealing with the same underlying condition, just expressed through different genes and hormone pathways.
It Tends to Run in Families
PCOS clusters in families, and researchers have been studying the genetic side of it for years. The World Health Organization notes that PCOS runs in families, though it can still cause very different symptoms from one relative to the next.
A study published in PMC looked at 273 women with PCOS and found a family history of type 2 diabetes in 28.21% of them, compared to 19.20% in a control group without PCOS. The same study found that this pattern showed up more often on the mother’s side of the family than the father’s, which lines up with how hormone-related traits are often passed down.
The Genetic Piece of the Puzzle
NICHD-funded research has identified 19 possible gene variants linked to a higher risk of developing PCOS. These variants may explain why symptoms differ so much from person to person, since not everyone carries the same combination.
Interestingly, some of these same gene variants have been found in men, who then showed cardiac and metabolic symptoms similar to what women with PCOS experience. Researchers have also grouped PCOS into genetic subtypes. One NICHDfunded project identified a reproductive subtype, marked by higher reproductive hormone levels, and a metabolic subtype, marked by higher body mass index, insulin, and glucose levels. A separate project identified four distinct symptom clusters tied to different genetic patterns, ranging from an obesity and insulin resistance cluster to an inflammation-linked cluster with lower blood platelet markers.
Insulin Resistance Is a Major Driver
Insulin resistance plays a central role in PCOS for a large share of women. When cells stop responding normally to insulin, the body produces more of it to compensate. That excess insulin pushes the ovaries to make more androgens, which are hormones like testosterone.
The Endocrine Society explains that insulin resistance or elevated insulin levels can worsen androgen excess, which is already a core problem in PCOS. A review in NCBI’s PMC adds that this process happens partly because insulin-sensitive tissues, like fat and muscle, respond poorly to insulin in women with PCOS, whether or not they are at a higher weight.
Excess Androgens and Hormone Signaling
Androgen excess shows up in an estimated 60% to 80% of women with PCOS, according to the Endocrine Society, and in most cases, the ovaries themselves are the source. High androgen levels interfere with the signals that trigger ovulation.
Cleveland Clinic explains that this disruption is what leads to irregular periods in the first place. When eggs are not released regularly, small, fluid-filled follicles can build up on the ovaries, which is where the older name for the condition came from.
Hormone Exposure Before Birth
Some of the newest research looks even earlier, before birth. NICHD-supported animal studies suggest that exposure to elevated androgen levels in the womb may increase the likelihood of developing PCOS-like features later on. This is still an active area of research, but it points to PCOS having roots that start well before puberty for some women.
A related and newer angle is epigenetics, meaning changes in how genes are switched on or off rather than changes to the genes themselves. A review in NCBI’s PMC points to epigenetic regulation, shaped by conditions in the womb or by later factors like lifestyle and body weight, as a possible piece of the PCOS puzzle. It is early science, but it helps explain why genetics alone do not tell the whole story.
Weight and Lifestyle: Amplifiers, Not Root Causes
Body weight often gets blamed as the cause of PCOS, but the research tells a more layered story. The CDC lists being overweight as a factor that may contribute to PCOS, alongside family history, not as the sole cause.
The same PMC review found that obesity tends to amplify insulin resistance that is already present in PCOS, rather than create it from nothing. It also notes that some women with a lower body weight and classic PCOS still show insulin resistance, while some women at a higher body weight do not. Genetics and hormone signaling set the stage; weight and lifestyle can make symptoms more pronounced.
A Simple Way to Support Hormone Balance Day to Day
No supplement can change a person’s genetics or reverse PCOS, and it’s worth being skeptical of anything that claims otherwise. What some women do look for is everyday support for the systems involved in hormone regulation. Real Science Nutrition’s Ovarian Support is a nitric oxide-focused formula built to support healthy circulation and normal endocrine function, both of which are closely tied to how the body manages hormone signaling. It is meant to work alongside a healthy lifestyle and medical guidance, not in place of either.
The Bottom Line
PCOS develops from a mix of genetics, insulin resistance, elevated androgens, and possibly hormone exposure before birth, with weight and lifestyle acting as amplifiers rather than root causes. Because the causes overlap in different ways for different women, there is no single test that explains “why” for any one person. Understanding which pieces apply to your own situation is usually the first step toward a treatment plan that actually fits.