You've no doubt heard about the 'criminal gene'.

It is the basis for so many stories in pop culture - TV, movies and books.

It's the idea that there might be a genetic marker that could allow us to know if someone is more likely to commit crime, especially violent crime, than someone who doesn't have this genetic marker.

So is this a work of fiction or something that actually exists?

It's one of Alex's favourite (it isn't) topics, so buckle in!