Why does a perfume smell different on different people?

It is one of the most frequent questions in the world of perfume — and one of the most fascinating. Two people wearing the same perfume can have very different olfactive experiences. This phenomenon is real, measurable, and is explained by several complementary mechanisms.

The role of skin pH

The pH of the skin varies between individuals (between 4.5 and 6.5 at the surface). Yet some aromatic molecules are sensitive to pH variations: they degrade, evaporate faster or bind differently to skin proteins. The result: the same formula can give a result perceived as more floral, more woody or more musky depending on the wearer.

The skin microbiome

Every individual has a unique skin microbiome — a community of micro-organisms (bacteria, yeasts) specific to their skin. These micro-organisms interact with the perfume's aromatic molecules, metabolising them differently. This interaction produces odorous by-products specific to each person.

It is one of the leads put forward to explain why a perfume “does not suit” some people. The subject is still little studied: the popular idea that everyone has their own natural perfume is only partially supported.

Temperature and hydration

Skin heat speeds up the evaporation of aromatic molecules. People with warmer skin (physical activity, slight fever, fast metabolism) may perceive their perfume as more intense and more volatile. Skin moisture slows this evaporation and extends the perfume's longevity.

Olfactory genetics

The human olfactory system relies on about 400 active olfactory receptors, encoded by a family of genes — the olfactory receptor genes (OR genes). These genes vary considerably from one individual to another: there are thousands of allelic combinations in the human population.

These genetic variations explain very real differences in perception: some people cannot perceive the smell of white musk (specific anosmia), and androstenone, for example, smells of urine to some, of sweet floral to others, and of nothing at all to still others, depending on a variation in the gene of a single receptor (OR7D4). Learning and culture then modulate these biological differences.

The psychological and memory aspect

Smell is the only sense whose signals reach the cortex without a compulsory thalamic relay, and join very directly the limbic system — the part of the brain linked to emotions and memory. This proximity contributes to the power of olfactory memories: a smell can instantly awaken an emotion or a memory decades old.

This connection also means that our appreciation of a perfume is strongly influenced by our personal history. A perfume that evokes a positive memory tends to be perceived more positively than a neutral one. And two people with different histories will react differently to the same perfume, even if their physico-chemical perception is identical.