Androgenetic alopecia, better known as male pattern baldness, affects an estimated half of men by middle age and up to 80% by their 80s. The "it comes from your mother's side" folk wisdom exists for a real reason: the androgen receptor (AR) gene sits on the X chromosome, which men inherit exclusively from their mothers, and AR was the very first gene locus ever linked to baldness. But treating that as the whole story badly understates how the trait actually works.
It's Polygenic — Hundreds of Genes, Not One
A landmark 2018 study analyzing over 205,000 men in the UK Biobank identified 624 nearly-independent genetic loci associated with male pattern baldness. Of those, only 26 sit on the X chromosome — meaning the vast majority of the genetic contribution comes from ordinary autosomal chromosomes, inherited from both parents, not just the maternal line. A separate large GWAS found 287 independent genetic signals, of which only 40 were on the X chromosome. The AR locus remains the single strongest individual predictor identified — its effect size dwarfs any other single locus — but "strongest single locus" and "the whole story" are very different claims, and the paternal side of your family tree genuinely does matter.
What This Means for Prediction
Because so many loci contribute, researchers have built polygenic risk scores specifically for baldness prediction, achieving meaningful (though imperfect) accuracy at distinguishing men who will develop severe hair loss from those who won't, even before symptoms appear. This has real-world applications beyond personal curiosity — including, somewhat unusually, a documented research interest in forensic DNA phenotyping, using genetic data to predict physical appearance traits like baldness likelihood from crime-scene DNA samples.
Look at both sides of your family, not just your maternal grandfather. The AR gene on the X chromosome (inherited from your mother) carries real predictive weight, but the majority of the genetic contribution to baldness comes from autosomal genes you could inherit from either parent — which is exactly why bald fathers correlate with bald sons too, contrary to the old rule of thumb.
Should You Get Tested?
If early intervention matters to you — most hair loss treatments work considerably better started early, before follicle miniaturization becomes advanced — knowing your genetic risk profile before symptoms are obvious can inform a proactive conversation with a dermatologist, rather than a reactive one after significant loss has already occurred.
Your Baldness Risk Genes Are Already in Your Genome
Dante Labs' whole genome sequencing captures AR and other baldness-associated variants alongside hundreds of other trait and health results. Use code GENOME for 10% off.
Get Sequenced with Dante Labs → 10% off with code GENOMEFor more genes shaped by hormones and heredity, see our APOE gene spotlight and our broader guide to analyzing your raw genome data if you want to look up trait variants yourself.