Up to Roughly a Third of People Are Genetically Unable to Smell Certain Musks

Blind to one note, not to smell itself

Specific anosmia is the inability to smell one particular compound, or family of compounds, while smelling everything else normally. It's well documented for macrocyclic and nitro musks specifically, the molecules widely used in modern perfumery as substitutes for animal musk. Estimates for how much of the population is affected vary by study and by the specific musk molecule tested, ranging from roughly 5 percent up toward 40 percent for some compounds.

It's written into a specific gene

Research has traced musk-specific anosmia to variation in the olfactory receptor gene OR5AN1, which responds to macrocyclic and nitro musks. Certain gene variants simply don't trigger a response to those molecules at all, meaning some people can spray on a musk-heavy fragrance and, to them, it may as well not be there.