In 1973, historical novelist Naomi Mitchison published her second Science Fiction novel, Solution Three. Science had not featured much in her public persona until then, but it was very important in her thinking. Her Haldane father and brother were both distinguished scientists, and her three sons all became professors in different branches of science. This novel is dedicated to a Jim Watson, who turns out to be the author of The Double Helix - and that in turn is dedicated to Mitchison, who helped to edit it.In her post nuclear Holocaust world, overpopulation and feeding the people are the major problems. The third attempted Solution involves conditioned homosexual love for all, and the only babies born are clones of the best two individuals, Her and Him, born to favoured Clone Mums. Some'Professorial' scientists have refused to abandon marriage and heterosexual reproduction, and are an embarrassment. They have developed powerful new strains of cereals to feed the world, but ominous signs of failure and new diseases occur. Has this new world done enough to preserve gene pools in both humans and foodstuffs? Mitchison is one of the first to raise all the potential problems of GM crops: her novel remains urgent, thoughtful and relevant in today's world.Isobel Murray is Emeritus Professor of Modern Scottish Literature at the University of Aberdeen.