With the New Year, there's often a resolution or two to make a new you. But what makes you, you? Given that we share over 99.9% of our genes with each other, there's a lot of variety in that 0.01%. Just look around you now - no two people are alike! Is it just your genes or is there something else at play? In this edition of The Naked Scientists, Graihagh Jackson goes in search of what makes a person, an individual beginning by asking why her brother got sixpack abs and she didn't...