What’s your favorite smell? Do you know why it’s your favorite? Science says that it’s the structure of an odor molecule that dictates how we receive it, and new research has found that the general consensus on what’s considered "good" and "bad" supersedes our cultural background.

“Cultures around the world rank different odours in a similar way no matter where they come from, but odour preferences have a personal – although not cultural – component,” said Artin Arshamian, a researcher at the Department of Clinical Neuroscience, Karolinska Institutet, and author on a new study published in Current Biology.

The study enlisted noses from across the globe with the help of an international team who carried out their investigations both in experimental conditions and in the field. Those nose owners came from a wide range of backgrounds, including some Indigenous groups that had very little exposure to smells and foodstuffs outside of their own culture.

“We wanted to examine if people around the world have the same smell perception and like the same types of odour, or whether this is something that is culturally learned,” Arshamian explained.

“Traditionally it has been seen as cultural, but we can show that culture has very little to do with it.”

In total, 235 people were put to the test in ranking a range of smells, including ones outside of their lived “odor experience,” a term Arshamian uses to describe the cacophony of smells that surround our individual lifestyles.

Ranking smells based on pleasantness crowned a winner for universal appeal: vanilla. That’s not to say that vanilla was each participants’ favorite smell, but it was the one most universally ranked as being rather nice.

At the other end of the scale, something called isovaleric acid scored as the universally least favored smell. It’s found in foods like soy milk and cheese but also makes up part of the perfume of foot sweat.

The results appear to show that globally there is a degree of universal acceptance as to which odors are good and which are bad, but individual differences exist within each “odor experience” group. The researchers believe these intergroup disagreements are probably partly to do with the molecular structure (~ 41 percent) but are more heavily influenced (~54 percent) by learning or our genetic makeup.

A victorious day for vanilla’s molecular odor profile, then – but there’s still work to be done in establishing what it is these “pleasant” smells are actually doing to our brains.

“Now we know that there’s universal odour perception that is driven by molecular structure and that explains why we like or dislike a certain smell,” Arshamian concluded. “The next step is to study why this is so by linking this knowledge to what happens in the brain when we smell a particular odour.”