Oily skin has a genetic component, but it’s smaller than most people assume. A large twin study of over 2,000 individuals from 486 families in Korea estimated the heritability of sebum secretion at just 0.21, meaning roughly 21% of the variation in oiliness between people can be attributed to genetics. The remaining ~79% comes from environmental and lifestyle factors, including shared habits within families like diet and skincare routines.
So if your parents have oily skin and you do too, genes are part of the story. But they’re far from the whole story.
What the Twin Studies Actually Show
Twin studies are the gold standard for separating nature from nurture. By comparing identical twins (who share 100% of their DNA) with fraternal twins (who share about 50%), researchers can estimate how much of a trait is driven by genetics versus environment. The Korean study, which included 388 identical twin pairs and 82 fraternal twin pairs, found that genetics plays only a “mild role” in sebum secretion. The researchers noted that oiliness is controlled predominantly by environmental factors, especially shared environments among family members.
That last detail is important. If you and your siblings all have oily skin, it might feel like proof of a genetic link. But you also grew up eating the same foods, living in the same climate, and possibly using similar products. The study found that these shared environmental factors matter more than shared DNA. For comparison, skin color had a heritability of 0.44, more than double that of oiliness, making it a much more genetically determined trait.
The Genes That Do Matter
The genetic influence that does exist works primarily through hormones. Your oil glands, called sebaceous glands, are driven by androgens. Hormones like testosterone and DHEA bind to androgen receptors inside the oil-producing cells of your skin, stimulating them to make more sebum. People with total androgen insensitivity syndrome, where androgen receptors don’t function, produce almost no sebum at all. This confirms that the androgen-receptor pathway is the central mechanism controlling oil output.
What you inherit isn’t “oily skin” directly. You inherit things like the density of oil glands in your skin, how sensitive your androgen receptors are, and how efficiently your skin cells convert circulating hormones into their more potent forms. Your oil gland cells can actually synthesize active androgens locally from weaker precursors circulating in your blood, and they also have built-in mechanisms to prevent excessive hormone activation. Genetic variation in any part of this system can nudge your baseline oil production higher or lower.
Specific genes involved include MC5R, which plays a role in sebaceous gland function across mammals, and FADS2, which helps process the unusual branched-chain fatty acids found in sebum. Variants in these genes can subtly shift how much oil your skin produces and what that oil is composed of.
How Diet Amplifies or Quiets Oil Production
One of the most powerful non-genetic factors affecting oiliness is diet, and the mechanism is well understood. High-glycemic foods (white bread, sugary drinks, processed snacks) cause a spike in insulin and a growth hormone called IGF-1. This triggers a chain reaction inside your oil gland cells: a protein called FoxO1 gets shuffled out of the cell’s nucleus, which releases the brakes on several fat-producing pathways. The result is a measurable increase in sebum production.
This means two people with identical genetics can have noticeably different skin oiliness depending on what they eat. A diet heavy in refined carbohydrates essentially amplifies whatever genetic tendency you have toward oily skin, while a lower-glycemic diet can dial it back. This is one reason oiliness often changes dramatically during different life phases, even though your DNA stays the same.
Temperature and Climate Effects
Your environment has a direct, measurable effect on how much oil your skin produces. In a randomized crossover trial, researchers found that sebum secretion increased significantly at 32°C (about 90°F) compared to 22°C (72°F). Within just one hour at the higher temperature, sebum levels rose by roughly 19 micrograms per square centimeter. Participants reported their skin feeling oilier, stickier, and less refreshed in the heat, while cooler conditions made skin feel drier and tighter.
This helps explain why people who move from a cool climate to a tropical one often develop oilier skin, or why your skin feels greasier in summer. It also means that someone with a low genetic predisposition to oily skin might still struggle with excess oil simply because of where they live or work.
Hormonal Changes Over a Lifetime
Because oil production is driven by androgens, it shifts predictably at certain life stages. Sebum output ramps up during puberty when androgen levels surge, which is why oily skin and acne tend to appear together in the teenage years. Women often notice fluctuations tied to their menstrual cycle, pregnancy, or menopause. Men generally produce more sebum than women throughout adulthood because of higher circulating testosterone.
These hormonal shifts can make oily skin feel like it comes and goes unpredictably, but the pattern is consistent: when androgen levels rise (or when your skin becomes more sensitive to them), oil production follows. This is also why oiliness often decreases naturally with age as hormone levels decline.
What You Can Actually Control
Given that nearly 80% of oiliness is driven by non-genetic factors, there’s a lot of room to influence your skin’s oil output. The most impactful levers are diet, climate management, and skincare choices. Reducing your intake of high-glycemic foods can lower the insulin and IGF-1 signaling that drives sebum production. Keeping your skin cool and using lightweight, non-comedogenic products helps manage the environmental side.
For people with severely oily skin that doesn’t respond to lifestyle changes, prescription treatments can be remarkably effective. Isotretinoin, the most potent option, reduces sebum production by 90% or more, bringing oil levels down to what’s typically seen on infant skin. That level of reduction goes far beyond what any genetic predisposition could resist, which further illustrates the point: genes set a starting range, but the final outcome is highly modifiable.
If oily skin runs in your family, your genes likely gave you a slight nudge in that direction. But the habits your family shares, the foods you grew up eating, and the climate you live in probably matter more than the DNA you inherited.