One Direction are pretty much the biggest thing in music right now, whether you like it or not. The five lads, spawned from X Factor in 2010, have just made history by being the first ever UK group to have their album debut at number one in America - that's a pretty big deal!
However, before the fame (and endless stream of young, adoring fangirls) goes to their hairy heads, let's look back at pictures of the One Direction lads as fresh-faced kids. Sure, it wasn't long ago since they were actually kids, but how well can you spot them from their baby pictures?
Click on to have a go...