Children are more likely to choose a smaller reward now than wait for a better reward later, and genes are responsible for it, says a research conducted by Washington University School of Medicine researchers.

The impulsive behaviour, which doesn't let us delay gratification and makes us more , gets better with age, says the report.

During the research, 602 twins were studied and it was found that they were able to withhold immediate gratification as they grew older, so 18-year-olds were much better at "delay discounting" than their younger selves.

Delay discounting, the survey says, is the tendency to take a smaller reward immediately than wait for the bigger benefit that is due to happen later. And it's an inherited trait.

Identifying the genes and proteins for the code would help in finding reasons for addictions and other disorders that involve impulsive decision-making.

"It is tantalising to speculate that the associations between delay discounting and serotonin-related genes may ultimately point the way to new treatments for addictions and other disorders involving impulsive choice," said the researcher Andrey Anokhin in a press release.

However, he warned that "it is very early to link this speculation to a clinical application."

The report was presented at American College of Neuropsychopharmacology annual meeting in Hollywood, Florida.