Genes leave a sour taste in your mouth
If sucking on a slice of lemon sends shudders down your spine, blame your genes.
Researchers have found that our ability to taste sourness is strongly influenced by genetic factors.
The US and Australian team compared the abilities of 74 pairs of identical twins and 35 sets of nonidentical twins to taste saltiness and sourness.
Because identical twins have nearly identical genes and fraternal twins share about half their genes, genetically speaking, scientists often use twin studies to figure out how much genes affect individual characteristics.
In this case, the twins were asked to taste cups of water containing small amounts of sour citric acid, or salt.
The researchers kept increasing the concentration of the solution until the twins could recognise the taste.
By looking at how much the nonidentical twins' abilities to identify the tastes varied, and comparing them with the variations among identical twins, the researchers could tease out how important the genes are.
The results show that genes play quite a large role for tasting sourness, says Jonathan Hansen, a PhD student from the Queensland Institute of Medical Research, who took part in the study.
"Roughly half of the variability in the ability to taste sourness was being caused by genes," he says, with the rest caused by environmental factors.
But the ability to taste saltiness seems to have little or no genetic component.
We all have the same range of taste receptors on our tongue and mouth for the five basic tastes: salty, sour, sweet, bitter and umami (savory or brothy).
Yet scientists have long known that our ability to recognise these tastes varies from person to person.
"That's why some people find certain dishes delicious while others find them absolutely repulsive," Hansen says.
Knowing that genes influence our perception of sourness raises the possibility that scientists could one day identify the actual genes involved.
And that could help people tailor their diets, says lead author Wise.
"If we can understand how and why people differ in their taste perception, we might eventually be able to manipulate the taste of individual diets to help encourage healthy eating," he says.