Some distinct scents are found to be repulsive by everyone, but there are a few that people all perceive differently. While some people can smell these specific scents with ease, others can’t smell them at all. While some find these specific scents pleasant, others find them appalling. A pair of studies published August 1 in the online journal Current Biology have identified the genetic differences that result in smell sensitivity and perception variations among individuals.

The research, led by Sara Jaeger, Jeremy McRae and Richard Newcomb of Plant and Food Research in New Zealand, found that 4 of the 10 scents tested held a genetic association, which suggested our genetic make-up determines whether or not we can smell a specific compound. These 4 smells are all familiar for individuals that can smell them, although their names might not be. The scents included malt, blue cheese, apple and beta ionone that is particularly abundant in violets.

“We were surprised how many odors had genes associated with them. If this extends to other odors, then we might expect everyone to have their own unique set of smells that they are sensitive to. These smells are found in foods and drinks that people encounter every day, such as tomatoes and apples. This might mean that when people sit down to eat a meal, they each experience it in their own personalized way,” said Jeremy McRae.

When McRae and his colleagues compared the differences in the sensitivities between different human populations, they found no regional differentiation. That means a person in Asia is as likely to be able to detect one of these scents as a person in Europe or Africa. Additionally, the ability to smell one of these compounds does not predict the ability to smell another.

What the researchers also found was that the genetic variants associated all lie in or near genes that encode odorant or olfactory receptors. Odorant receptor molecules sit on the surface of sensory nerve cells in the nose. When these molecules bind with compounds in the air, the nerve cells send signals to the brain which result in our perception of smell.

“Knowing the compounds that people can sense in foods, as well as other products, will have an influence on the development of future products. Companies may wish to design foods that better target people based on their sensitivity, essentially developing foods and other products personalized for their taste and smell,” said Richard Newcomb.