Guide · The evidence
Does genetics affect how you respond to anabolic steroids?
Genes shape the machinery that steroids work through. This page goes through the genes researchers have studied in connection with testosterone, what was found, and how strong the evidence is, without overselling any of it.
Quick answer
Partly, in the biology, but not in a way any test can predict. Genes such as SHBG, CYP19A1 (aromatase), UGT2B17 and the androgen receptor influence natural hormone levels and how testosterone is handled. Almost no research has studied them in people who use anabolic steroids, and no genetic test predicts response or side effects.
- Strongest evidence: SHBG for testosterone and SHBG levels, CYP19A1 for oestradiol, UGT2B17 for testosterone in urine.
- The androgen receptor CAG repeat has small effects in people and hasn't been studied in steroid users.
- What you take, how much and for how long matters far more than any gene.
The genes, rated by evidence
| Gene | What it does | What research found | Evidence |
|---|---|---|---|
| SHBG | Makes sex hormone binding globulin, which carries testosterone in the blood. | The strongest genetic influence on SHBG and total testosterone in men. Some variants also change how tightly SHBG binds testosterone. | Well replicated |
| CYP19A1 | Makes aromatase, which turns testosterone into oestradiol. | The strongest genetic influence on oestradiol in men, with around 5 to 10% differences per variant. | Well replicated |
| UGT2B17 | Makes the enzyme that prepares testosterone to leave in urine. | A common whole-gene deletion sharply lowers testosterone in urine and changes urine T/E ratios. | Well replicated |
| AR (CAG repeat) | The androgen receptor, which testosterone and DHT act through. | Repeat length changes receptor activity in the lab; in people the effects on testosterone, prostate and hair are small. Not studied in steroid users. | Some evidence |
| AR / EDA2R region | The X-chromosome region around the androgen receptor gene. | One of 63 regions linked to male-pattern baldness, which together explain about 39% of its variation. | Some evidence |
| SRD5A2 | Makes 5-alpha reductase type 2, which turns testosterone into DHT. | The V89L variant lowers enzyme activity in the lab; its effect on DHT in people is unresolved. | Early research |
| ESR1 | The oestrogen receptor. | Two much-studied variants had no effect on bone density in a pooled analysis of 18,917 people. | Early research |
| CYP3A4 | A liver enzyme that breaks down many medicines. | CYP3A4*22 lowers the enzyme and has been studied for statins. We found no evidence linking it to testosterone or anabolic steroids. | Early research |
Hormone levels are partly inherited
A UK Biobank study of 425,097 people found 2,571 genetic associations with testosterone and related traits, each small, and showed the genetics differ between men and women.[1] The single strongest influence on men’s total testosterone sits by the SHBG gene: in nearly 9,000 men, each copy of the T allele of rs12150660 went with higher SHBG and higher testosterone, and men carrying three or more low-testosterone alleles across three regions were about six times as likely to have low testosterone.[2] Even so, the twelve genetic regions found to affect SHBG together explain only about 16% of its genetic variation in men.[3]
The receptor: big in the lab, small in people
The androgen receptor’s CAG repeat changes how active the receptor is in laboratory experiments. In 181,217 men in UK Biobank, its effects on testosterone, bone, hair and disease were small, and circulating testosterone mattered more.[4] Read the CAG repeat guide.
The gap: steroid users haven’t been studied
Nearly all of this research is in men’s natural hormones or in men prescribed testosterone. We found no study of androgen receptor repeats in anabolic steroid users. An Endocrine Society statement notes that most people using performance-enhancing drugs aren’t athletes but recreational weightlifters, and calls for more research on them.[5] Until it exists, honest genetic reports describe variants and their evidence, and stop there.
Whether steroids are safe for you, which side effects you’ll get, or what to take. Why not.
See your own variants
If you have 23andMe, AncestryDNA or MyHeritage raw data, the raw DNA hormone gene checker shows your genotype at studied variants in SHBG, CYP19A1, SRD5A2, the AR region, ESR1 and CYP3A4, in your browser.
Questions
Does genetics affect how you respond to steroids?
Genes shape the biology steroids act on, such as the androgen receptor, aromatase and SHBG, and they explain part of the natural differences in testosterone between men. But almost no research has looked at genes in people who use anabolic steroids, and no genetic test has been shown to predict someone's response or side effects.
Why do some people respond better to steroids than others?
Mostly because of differences in what is taken, how much, for how long, training, diet, sleep, age and starting body composition. Genes probably play a part, but which genes and how much hasn't been measured in steroid users.
Are some people genetically high responders to steroids?
The idea is popular, but there's no validated genetic test for it. Variants that change androgen receptor activity or SHBG have small effects in studies of natural hormones and prescribed testosterone, and haven't been tested as predictors in steroid users.
Is testosterone level genetic?
Partly. A UK Biobank study of 425,097 people found 2,571 genetic associations with testosterone and related traits. Each has a small effect; together they explain part of the difference between people, alongside weight, age and health.
Is gynaecomastia genetic?
Genes influence how much testosterone becomes oestradiol, but no gene test predicts gynaecomastia. On steroids, the amount of testosterone being converted matters far more.
Sources
- Ruth KS et al. Using human genetics to understand the disease impacts of testosterone in men and women. Nat Med 2020;26:252–58.
- Ohlsson C et al. Genetic determinants of serum testosterone concentrations in men. PLoS Genet 2011;7:e1002313.
- Coviello AD et al. A genome-wide association meta-analysis of circulating sex hormone-binding globulin. PLoS Genet 2012;8:e1002805.
- Sasako T et al. The influence of trinucleotide repeats in the androgen receptor gene on androgen-related traits and diseases. J Clin Endocrinol Metab 2024;109:3234–44.
- Pope HG Jr et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev 2014;35:341–75.
- Heilmann-Heimbach S et al. Meta-analysis identifies novel risk loci and yields systematic insights into the biology of male-pattern baldness. Nat Commun 2017;8:14694.
- Ioannidis JPA et al. Differential genetic effects of ESR1 gene polymorphisms on osteoporosis outcomes. JAMA 2004;292:2105–14.
Keep reading
- Guides
Can a DNA test show steroids are safe?
The honest answer, and what genetic tests and blood tests can each tell you.
- Tools
Raw DNA hormone gene checker
See your genotypes at studied hormone-gene variants from a 23andMe or AncestryDNA file, read in your browser.
- Compare
DNA test vs blood test
What a blood test and a genetic test can each tell you about your hormones, side by side.
For information only, not medical advice. GeneticEdge does not recommend or endorse anabolic steroid use, and no genetic test can tell you whether steroids are safe for you. Talk to a GP or pharmacist about your health. Last reviewed 30 October 2026.