May 2, 2012 -- If you find the smell of pork revolting, it could be because that's how you're genetically programmed to perceive it, according to a new study.
Scientists found that there's a gene responsible for how a compound in pork smells to humans. The gene determines whether pork smells like ammonia, urine and sweat, or if it smells more like vanilla. The compound, androstenone, is similar to testosterone and found in high concentrations in male pigs.
The researchers gave study subjects pork containing androstenone and separated them into two groups -- those who found the smell offensive and those who didn't. Genetic analysis of the subjects revealed that those who didn't like the smell had two copies of a specific form of a gene known as OR7D4. The others had only one copy of the gene.
But, it turns out, most people don't even notice the smell of androstenone.
"In North America and Europe, pigs are castrated, so the concentration of androstenone is quite low," said Hiroaki Matsunami, a co-author and associate professor of molecular genetics and microbiology at Duke University Medical Center. "The only time you find a high concentration of androsteone is when you eat wild boar meat."
That could soon change, however. The researchers noted that the European Union is considering a ban on castration because of concerns over animal welfare, and this debate has rekindled interest in how humans perceive the smell of pork and why two people may smell it differently.
"The data raise the possibility that more consumers will dislike male meat as a result of a castration ban," the authors wrote.
Androstenone is also found in other male animals, but it's found in particularly high amounts in swine, Matsunami said.
How food smells, as everyone knows, also affects how food tastes, and this research helps confirm just how much the nose knows when it comes to taste.
"When food is in your mouth, odors come from the back of the throat up to the nose," said Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia. "Taste is very complex. It depends on smell and other factors, such as personal experience and genetic background."
While the study is particularly interesting to scientists, it also demonstrates how genes play a role in many biological processes, including the senses.
"It's a very clear example of how people live in different sensory worlds, and some of the basis of that is our genetic differences," Beauchamp said.
ABC News' Dr. Samantha Meaney contributed to this report.