VEGETARIANS’ dislike of meat may be in their DNA, according to a study showing that some people are genetically predisposed find the smell off-putting.

Researchers found the reason some people don't like the taste of meat may be because their genes cause them to smell it more intensely.

Scientists at Duke University Medical Centre in the United States, working with colleagues in Norway, found that about 70 per cent of people have two functional copies of a gene linked to an odour receptor that detects a compound in male mammals called androstenone, which is common in pork.

The researchers said people with one or no functional copies of the gene can tolerate the scent of androstenone much better than those with two.

Doctor Hiroaki Matsunami, professor of molecular genetics and microbiology, had previously discovered and described the genetics of the odour receptor for androstenone (OR7D4).

However, it wasn't until a group of pork scientists in Norway contacted him that he launched an experiment to learn more precisely at a genetic level how humans perceive the smell of meat.

The Norwegian team had practical reasons for the study. It was concerned what might happen in Europe if a castration method for swine were outlawed. Currently, female pork meat and castrated male pork meat are sold in Europe. The researchers were curious how shoppers might respond to meat from non-castrated males.

The level of androstenone in noncastrated pigs ranges up to 6.4 ppm. In Norway the level of androstenone in immunocastrated (using hormones) pigs is from 0.1 to 0.2 ppm, and in surgically castrated pigs the rate approaches zero.

Dr Matsunami said the findings raise the possibility that more people will dislike meat if castration is banned and more meat from non-castrated animals is sold.

A total of 23 subjects were recruited: 13 consumers and 10 professional sensory assessors. When they were divided into sensitive and insensitive cohorts, according to a smell test that was previously devised, all of the androstenone-sensitive subjects had the RT/RT genotype, with two copies of the functional RT gene.

Dr Matsunami said: "I was surprised at how cleanly this experiment showed who smelled what.

"The results showed that people with two copies of the functional variant of the gene for that odor receptor thought that the meat smelled worse with higher levels of androstenone added."

For the experiment, the researchers added only biological levels of androstenone to existing pork meat, up to the limit of what might be found in male wild boars.

Dr Matsunami said it would be fascinating to see results done on certain populations, including people in the Middle East, where pork has been omitted from diets for centuries.

He added: "I would also like to know about odour receptor variants in indigenous populations, such as people who live near the Arctic Circle and who never eat these meats. What is their genotype?"

He said vegetarians as a group may also have a genetic predisposition against the smell of meat, but all of these ideas need to be scientifically studied.

Dr Matsunami also speculated whether meat inspectors with both copies of the functional variant, who presumably would be more sensitive to higher levels of androstenone, might make different decisions in their jobs.

The findings were published online in the journal PLoS ONE.