Are You Born With PCOS? Causes Explained

Are you born with PCOS, or does it develop later in life? Polycystic ovary syndrome (PCOS) has its roots in genetics, meaning the biological predisposition is present from conception. However, the hormonal changes that trigger recognisable symptoms typically emerge during puberty rather than at birth. Understanding whether PCOS is inherited, acquired, or both helps explain why it runs in families, why symptoms vary so widely between individuals, and why lifestyle factors can influence severity without being the underlying cause. This article explores the genetic, hormonal and biological foundations of PCOS.

Are you born with PCOS or does it develop over time?

People are born with a genetic predisposition to PCOS, but symptoms and hormonal changes typically emerge during puberty rather than at birth. A newborn cannot be diagnosed with PCOS even though the biological foundations may already be present.

People with PCOS are born with a genetic predisposition to the condition, but the symptoms and hormonal changes that define it typically emerge and become apparent during puberty rather than at birth. PCOS (polycystic ovary syndrome) is not present in a fully expressed form from the moment of birth. Instead, the underlying biological blueprint, including inherited variations in genes that govern hormone production and insulin signalling, is present from conception. It is the hormonal shifts of puberty that appear to activate or unmask these tendencies, leading to the recognisable features of the condition.

Because PCOS cannot be identified before puberty, it is diagnosed using clinical and biochemical criteria in adults, most commonly the Rotterdam criteria, which require two of the following three features: irregular or absent ovulation, clinical or biochemical signs of elevated androgens, and polycystic ovarian morphology on ultrasound, after other causes have been excluded.^[1][4] This means a newborn cannot be diagnosed with PCOS, even though the biological foundations may already be present.

Research also suggests that exposure to elevated androgens in the womb may influence how the condition later presents. This hypothesis is supported by animal model data; human evidence remains limited and is still developing. In this sense, PCOS is neither purely congenital nor purely acquired: it sits at the intersection of inherited biology and the hormonal environment a person encounters across their lifetime.

Understanding this helps to explain why PCOS can run strongly in families, why it varies so widely in severity between individuals, and why lifestyle factors such as weight, diet and physical activity can influence how prominently symptoms appear, without being the root cause. For anyone concerned about symptoms, a GP is the appropriate first point of contact for assessment and diagnosis. The NHS and NICE both publish patient-facing information on PCOS that can help people understand what to expect from an assessment.

What causes PCOS, genes, hormones, or lifestyle?

PCOS is caused by a combination of genetic susceptibility, hormonal dysregulation and insulin resistance, rather than any single factor. Lifestyle factors can worsen symptoms but do not cause PCOS without an underlying genetic predisposition.

PCOS is caused by a combination of genetic susceptibility, hormonal dysregulation and, to a lesser extent, environmental and lifestyle influences, rather than any single factor acting alone. The condition is characterised by elevated androgen levels (sometimes called male hormones, though they are present in all people), irregular or absent ovulation, and, in many cases, insulin resistance. These features interact with one another in ways that can amplify symptoms over time.

Genetics plays a central role. Studies of twins and families consistently show that PCOS clusters in biological relatives, with first-degree female relatives of someone with PCOS having a notably higher likelihood of developing the condition themselves.^[6][7] Several genes involved in androgen synthesis, insulin signalling and gonadotrophin regulation have been implicated, though no single gene has been identified as the definitive cause. The condition is considered polygenic, meaning multiple genetic variants each contribute a small amount of risk.^[8][9]

Hormonal factors are equally important. Disruption to the normal pulsatile signalling between the hypothalamus, pituitary and ovaries leads to impaired follicle development. Elevated luteinising hormone (LH) activity is one feature seen in some people with PCOS, though the LH to FSH ratio is not a diagnostic criterion and is not consistently abnormal across all cases. Insulin resistance, which is present in a significant proportion of people with PCOS regardless of body weight, causes the pancreas to produce more insulin, which in turn stimulates the ovaries to produce more androgens.^[14][15] This creates a self-reinforcing cycle.

In adults, PCOS is diagnosed using the Rotterdam criteria: two of the following three features must be present after other causes have been excluded: oligo-ovulation or anovulation; clinical or biochemical hyperandrogenism; and polycystic ovarian morphology on ultrasound. Initial investigations in primary care typically include a pregnancy test, androgens and sex hormone-binding globulin (SHBG) or free androgen index, TSH, prolactin, and screening for metabolic risk (HbA1c or fasting glucose, and lipids), with 17-hydroxyprogesterone considered where congenital adrenal hyperplasia needs to be excluded. NICE CKS guidance on PCOS provides a detailed framework for primary care assessment.

Lifestyle factors such as excess weight, a sedentary routine and a diet high in refined carbohydrates can worsen insulin resistance and thereby intensify symptoms, but they do not cause PCOS in someone without the underlying genetic predisposition. Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online consultations, with prescriber review and pharmacist support, for those exploring management options for conditions linked to metabolic health.

The genetic and biological roots of PCOS explained

PCOS involves multiple inherited gene variants affecting hormone regulation, insulin signalling and reproductive function, making it a polygenic condition. Insulin resistance further amplifies androgen production by reducing sex hormone-binding globulin and stimulating the ovaries.

The genetic architecture of PCOS is complex, involving multiple inherited variants that together influence how the body regulates hormones, responds to insulin and controls reproductive function. Genome-wide association studies (GWAS) have identified a number of loci associated with PCOS risk, including regions linked to LH receptor signalling, androgen biosynthesis and insulin pathway regulation.^[8][9] This is association-level evidence, and the field continues to evolve; no single mutation is responsible. Rather, it is the cumulative effect of several variants that shapes an individual's susceptibility.

Beyond inherited DNA, there is growing but still limited evidence that epigenetic factors, meaning changes in how genes are expressed without altering the underlying sequence, may also contribute. Exposure to elevated androgens in the womb has been shown in animal models to programme the developing hypothalamic-pituitary-ovarian axis in ways that predispose offspring to PCOS-like features. Human evidence for this mechanism remains preliminary, and these findings should be understood as hypothesis-generating rather than established fact.

Biologically, the condition involves a disruption in the normal feedback loop between the brain, the pituitary gland and the ovaries. Elevated LH activity from the pituitary can stimulate the ovarian theca cells to produce excess androgens.^[17][18] These androgens interfere with normal follicle maturation, preventing ovulation and leading to the accumulation of small, immature follicles that give the ovaries their characteristic appearance on ultrasound. It is important to note that polycystic ovarian morphology on ultrasound is common and is not diagnostic on its own; it must be interpreted alongside clinical and biochemical findings, as NICE CKS guidance makes clear. Insulin resistance compounds the hormonal disruption by further stimulating androgen production and reducing levels of sex hormone-binding globulin (SHBG), which normally keeps free androgens in check.^[13][14] Together, these mechanisms explain why PCOS presents with such a wide range of symptoms across different individuals.

Why do PCOS symptoms often appear in the teenage years?

PCOS symptoms emerge during puberty because hormonal changes activate a genetic predisposition that has been present since birth. Diagnosing PCOS in adolescents requires caution, as irregular cycles and polycystic morphology can be normal variants in early adolescence.

PCOS symptoms most commonly become apparent during puberty because the hormonal changes of this period are what trigger the expression of an underlying genetic predisposition that has been present since birth. Before puberty, the hypothalamic-pituitary-ovarian axis is relatively quiescent, meaning the hormonal environment does not yet activate the mechanisms that produce PCOS features. Once puberty begins, the system becomes active, and in those with the relevant genetic background, the dysregulation that defines PCOS can emerge.

Diagnosing PCOS in adolescents is more complex than in adults. NICE CKS and the 2023 International Evidence-Based Guideline for PCOS (Monash/ESHRE/ASRM) both advise caution when applying the Rotterdam criteria to teenagers.^[2][3] Features such as polycystic ovarian morphology on ultrasound and mild androgen excess can be normal variants in early adolescence, and ultrasound is not recommended as a diagnostic tool in this age group. In adolescents, a diagnosis generally requires persistent ovulatory dysfunction alongside clinical or biochemical hyperandrogenism; irregular cycles alone in the first one to two years after the first period are not sufficient for diagnosis, as some irregularity is expected during this time.^[21][22]

Other symptoms that may appear during the teenage years include acne, excess facial or body hair (hirsutism) and, in some cases, weight gain or difficulty managing weight. These can have a significant impact on self-esteem and mental wellbeing, and it is important that young people experiencing them are taken seriously and offered appropriate assessment.

Anyone concerned about these symptoms should speak to their GP. Reasons to seek prompt review include: periods that remain irregular or absent beyond the expected post-menarche adjustment period; amenorrhoea lasting more than three months; hirsutism that is severe or has appeared rapidly; signs of virilisation; significant distress or impact on daily life; or concerns about fertility. A GP can arrange relevant blood tests, exclude other causes, and refer to a specialist in reproductive endocrinology or gynaecology where appropriate. Early identification allows for timely support and management, which can help to reduce the longer-term metabolic and reproductive effects associated with untreated PCOS, including increased risk of metabolic syndrome, type 2 diabetes and, with prolonged anovulation, endometrial hyperplasia.^[24] The NHS PCOS pages and NICE CKS provide further information on symptoms, investigations and when to seek care.

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