[Codex Excerpt] So Every GSC are bald.
>AND ALL SHALL RISE AS ONE
>Some cultists are truly monstrous, skulking along dank tunnels with robes or hessian sacks covering their hybrid anatomies.
>Others are merely pallid and bald, able to pass for loyal citizens whilst their wyrm-form tattoos remain hidden. These latter- generation cultists mingle with the herd like wolves in sheep’s clothing, working so hard amongst the crumbling machineries of Mankind’s industry that none spare them a second glance, but under their work fatigues and rough miner’s apparel, they all bear the mark of the alien.
>Once their subculture becomes strong enough, and all is in place for their great uprising, the Genestealer Cult will make its play. The militant throng boils by the thousand from sewers,
>tunnels and basements, simultaneously emerging from hiding places in the spires high above like insects teeming from a hidden nest. Those wise enough to flee find the city streets and
>arterial passageways blocked by burning wreckage or by packs of hybrid creatures waiting to pounce.
While I’ve seen various accounts of GSC characters with hair in novels or games, it seems officially established that they are naturally hairless. One might joke that a biophagus could have concocted a hair-growth serum to aid infiltration—but let’s be honest: if they had, they’d be the wealthiest individual in the 40K galaxy, second only to Jimmy Space himself.— It’s far more likely that those specific characters are relying on wigs or hair transplants.
To me, if entire GSC are genetically bald, that feels just as weird as the lore about biophagus could contaminate entire regiment’s food chain and effectively replicate the Genestealer’s kiss on a massive scale.