If you could be tested to see if you carry inherited genes for a fatal disease, would you? That's a dilemma facing more and more people as scientists keep making breakthroughs in genetic testing. Eileen Merriman is an Auckland-based haematologist whose past novels for adults and young adults often touch on medical issues she comes across in her work life. In Double Helix, Jake is an aspiring doctor whose mother had Huntington's disease. But he is conflicted over whether or not to see if he's inherited the condition. It comes to a head when he and his partner Emily consider having children. Lynn Freeman talks with Eileen Merriman about blending fact and fiction.