New York: The answer of why some people have a sweet tooth while others avoid extra servings of desserts lies in your genes, scientists say.

Just as people born wIth a poor sense of hearing may need to turn up the volume to hear the radio, people born with a weak sweet taste may need an extra teaspoon of sugar in their coffee to get the right punch, researchers from the Monell Chemical Senses Center in Philadelphia said.

A single set of genes affects a person’s perception of sweet taste, regardless of whether the sweetener is a natural sugar or a non-caloric sugar substitute, they found.

“Our work suggests that part of what determines our perception of sweetness is inborn in our genetic makeup,” said study author Danielle Reed, behavioural geneticist at Monell.

To reach this conclusion, researchers tested 243 pairs of identical twins, 452 pairs of fraternal twins and 511 unpaired individuals.

Each person tasted and then rated the intensity of four sweet solutions: fructose, glucose, aspartame, and neohesperidine dihydrochalcone (NHDC).

The first two are natural sugars while the latter two are synthetic, non-caloric sweeteners.

Studying twin pairs allowed the researchers to determine how much influence the twins’ shared genetics contributed to their perception of sweet taste intensity.

The results showed that genetic factors account for approximately 30 percent of person-to-person variance in sweet taste perception.

Those who perceived the natural sugars as weakly sweet experienced the sugar substitutes as similarly weak.

“This suggests that there may be a shared pathway in the perception of natural sugar and high-potency sweetener intensity,” noted the authors in the journal Twin Research and Human Genetics.

The study also found little evidence for a shared environmental influence on sweet perception.

Assuming twin pairs took part in communal meals during childhood, this result challenges the common belief that access to foods high in sugar may make children insensitive to sweetness.

“Our findings indicate that shared experiences such as family meals, had no detectable ability to make twins more similar in taste measures,” Reed explained.

Understanding the genetic differences that affect an individual’s perception of sweetness may eventually help food manufacturers reduce the amount of sugars and sweeteners they add to food, the authors noted.