Who am I? Why am I here? What makes me human? These fundamental questions about our existence and sense of self have dominated philosophical debate for hundreds of years. Modern science is beginning to unravel some of the answers - opening up further conundrums and surprises along the way.

On Monday 26 June 2000, science took a giant step towards understanding what makes us who we are when the International Human Genome Consortium announced that 90 per cent of the human genome - the 'working draft' - had been sequenced. The entire sequence was placed in public databases on the internet so that researchers could start mining it for information about what makes us tick. The Wellcome Trust Sanger Institute, the only British organisation involved, carried out nearly one-third of the work, making it the largest single contributor to the international project.

The era of genomics - the detailed study of genomes - was underway. By identifying specific genes that code for particular physical traits or 'phenotypes', scientists can start to address some of our questions about ourselves. To what extent we are a product of inescapable genetic influences, for example? What roles do our upbringing and lifestyle choices play in forming our identities? How much choice do we really have when it comes down to who we are? Or is it all done for us by biology and/or the unique set of family and social circumstances each of us is born into?