THe conventional The way of making babies is no secret: a father produces a sperm which, when he comes into contact with the egg of a mother, gives birth to an embryo containing genetic material from both parents. The process is popular but not universally accessible; The same sex couples cannot produce organic children together. Scientists have therefore long sought more ambitious recipes, especially those that remove the need for one or the other parent. They had some success: mice with two mothers and no father was reported in 2004. But creating animals with two fathers and no mother turned out to be much more difficult.