The songwriters behind some of One Direction's biggest smash-hits have admitted that they aim to make harmless "vanilla" pop music for the lads because they know it sells.

Carl Falk, Rami Yacoub and Savan Kotecha ('What Makes You Beautiful,' 'One Thing,' 'Live While We're Young') explained to Billboard that working on music for the heartthrobs is fairly straightforward as they have found a winning formula:

"It felt like everyone tried to do boy bands by going to the cool, hip producers who were coming up. We wanted to make it very vanilla. You're aiming for teens and tweens with boy-band guilty pleasure music. We weren't trying to be urban or rhythmic, and they happened to share the same vision," Kotecha admitted.

Falk added that it's important to create something that fans can cover using a guitar or sing along to on a homemade YouTube music video, so they try to incorporate memorable riffs and break downs:

"Each of the songs have signature riffs -- something so people can play YouTube versions of our songs. We wanted to do something where we didn't copy anything right off. We're trying to do our own thing a little bit, even if it's just guitar parts."

Watch Barbara Walters' recent interview with One Direction here: