Our genomes are more than just an instruction manual for our bodies. They are maps, diaries, history books and medical records of our and our ancestors' lives.....if you know how to read them. In this programme and the next Adam Rutherford is joined by UCL geneticist Lucy van Dorp and other scientists who are cracking these genomic codes to tell the human story. This week they explore how sex and disease over the past few thousand years has left indelible marks on our DNA.