Is Your Low Testosterone Genetic? What DNA Testing Can Reveal

If you've had low testosterone diagnosed, you might wonder: is this just bad luck, lifestyle factors, or did I inherit this? Genetic testing can provide some answers. Certain genetic variants affect testosterone production and androgen receptor sensitivity, but the picture is more complicated than most people realise.

The honest truth: genetics matters for testosterone, but lifestyle and metabolic health matter far more. You can have genetic variants predisposing to lower testosterone and still have excellent testosterone levels through optimisation. Conversely, you can have genetics favouring high testosterone and destroy it through poor lifestyle.

But understanding your genetic architecture is useful for personalising your approach.

Androgen Receptor Polymorphisms: CAG Repeats

The androgen receptor gene contains a variable stretch of CAG repeats. The number of repeats (ranging from about 8 to 30) affects androgen receptor sensitivity.

Shorter CAG repeats are associated with:

• Higher androgen receptor sensitivity
• Better response to a given testosterone level
• Potentially higher baseline testosterone production
• Greater muscle gain responsiveness to training

Longer CAG repeats are associated with:

• Lower androgen receptor sensitivity
• Larger testosterone requirements to achieve the same biological effects
• Less robust training response to a given testosterone level
• Higher risk of age-related testosterone decline

This is one of the most studied genetic variants in men's health. The effect is real but modest - it explains roughly 3-5% of the variance in testosterone levels and androgen-dependent traits.

If you have longer CAG repeats, this doesn't mean you're destined to low testosterone, but it does mean you may need to be more aggressive about optimisation to achieve excellent testosterone levels.

SHBG Gene Variants

Sex hormone-binding globulin (SHBG) is the protein that binds testosterone and reduces its bioavailability. Genetic variants in the SHBG gene affect how much SHBG your body produces.

Variants associated with higher SHBG production mean:

• More of your testosterone gets bound
• Lower free (bioavailable) testosterone
• Potentially lower symptoms despite adequate total testosterone

Variants associated with lower SHBG production mean:

• More testosterone remains free
• Higher bioavailability
• Greater androgen effects on target tissues

Like CAG repeats, SHBG variants explain only modest amounts of variance in testosterone, but they can help explain why two men with the same total testosterone feel very different.

CYP19A1 Gene and Oestrogen Synthesis

The CYP19A1 gene encodes aromatase, the enzyme that converts testosterone to oestrogen. Genetic variants affect aromatase activity.

Variants associated with high aromatase activity mean:

• More testosterone gets converted to oestrogen
• Lower effective testosterone
• Relative oestrogen excess
• Potential weight gain, mood changes, reduced sexual function

Variants associated with low aromatase activity mean:

• Less testosterone conversion to oestrogen
• Higher effective testosterone
• Potential oestrogen deficiency (concerning because oestrogen is also important in men)
• Potentially better muscle development

Aromatase activity is important because it's modifiable. If you have high aromatase activity, reducing oestrogen-to-testosterone ratio through resistance training, alcohol reduction, and potentially supplements (indole-3-carbinol from cruciferous vegetables, aromatase inhibitors if under medical supervision) can improve testosterone effectiveness.

LH Receptor Gene Variants

The LH receptor gene variants affect how responsive your Leydig cells are to LH signalling. LH stimulates testosterone production; poor LH receptor function means your testes don't respond as robustly.

Variants associated with better LH receptor function mean:

• Better testosterone production response to LH
• Potentially higher baseline testosterone

Variants associated with poorer function mean:

• Less testosterone production despite adequate LH
• Higher risk of age-related testosterone decline

These variants are less commonly tested than androgen receptors or SHBG, but they contribute to individual variation in testosterone.

What DNA Testing Actually Shows

When you get genetic testing for testosterone-relevant variants, you typically see:

1. Polygenic risk score: A combination of multiple variants predicting whether your genetic background favours higher or lower testosterone

2. Specific variant results: Details on androgen receptor CAG repeats, SHBG variants, CYP19A1, and potentially LH receptor variants

3. Interpretation: A risk category (low genetic predisposition, average, high predisposition for low testosterone)

What matters: this provides context for why your testosterone is what it is, but it doesn't predict your future testosterone. A man with "genetic predisposition to low testosterone" who trains hard, eats well, sleeps adequately, manages stress, and optimises minerals can easily maintain testosterone in the 500+ ng/dL range.

A man with "genetic predisposition to high testosterone" who is sedentary, overweight, sleeps poorly, and chronically stressed might have testosterone in the 300s.

Lifestyle and metabolic health trump genetics.

Practical Use of Genetic Testosterone Testing

If you get tested and find genetic variants predisposing to lower testosterone:

1. Don't panic: Genetic predisposition is not destiny. You still have substantial control through lifestyle.

2. Optimise aggressively: Focus on resistance training, adequate protein, good sleep, stress management, and micronutrient adequacy. If genetics are predisposing you to lower testosterone, these become more critical.

3. Monitor markers: Get blood work done (total testosterone, free testosterone, SHBG, oestrogen) to assess whether your actual hormones are affected.

4. Consider targeted interventions: If you have high aromatase gene variants, cruciferous vegetables and reducing alcohol are particularly important. If you have long CAG repeats, training emphasis on heavy resistance becomes more critical.

5. Plan for aging: If you have genetic predisposition to testosterone decline, start optimisation early. The decline will happen anyway; starting from an optimised baseline is better than optimising after decline.

The Genetics vs Lifestyle Reality

Studies comparing genetically identical twins raised in different environments show that:

• Lifestyle factors (diet, exercise, sleep) typically explain 2-3x more variation in testosterone than genetic factors
• Twin concordance for testosterone declines with age, suggesting lifestyle becomes increasingly important as you age

This means your genetic baseline matters, but how you live matters far more.

A man with genetic predisposition to low testosterone who lives optimally can outperform a man with high genetic predisposition who lives poorly.

Who Should Consider Genetic Testing for Testosterone

Genetic testing for testosterone-relevant variants is worth considering if:

1. You have low testosterone diagnosed (understanding genetic contribution helps explain why)
2. You have family history of low testosterone or erectile dysfunction (suggesting genetic predisposition runs in your family)
3. You're implementing major lifestyle changes and want context for why those changes matter for your specific genetics
4. You want to personalise supplementation and training approaches based on your specific genetic background

It's less essential if you're young, already doing well, or not concerned about testosterone status.

AlphaBiolabs offers genetic testing including testosterone-relevant variants: https://www.awin1.com/cread.php?awinmid=109866&awinaffid=2838304&clickref=&p=https%3A%2F%2Fwww.alphabiolabs.com

The key insight: if you discover you have genetic predisposition to low testosterone, this should motivate you to optimise lifestyle more aggressively, not to accept lower testosterone as inevitable. Your genes set a baseline; your lifestyle determines whether you reach it.