A baby syringe

The Human Fertilisation and Embryology Authority is considering whether to recommend legalisation of "mitochondrial replacement" techniques designed to avoid the transmission of mitochondrial diseases (Report, 17 September 2012). We believe the benefits to a small number of parents are heavily outweighed by the risks to the child and to society. This would be the first instance of regulatory approval for modification of the human germ line. There is a long-standing international consensus that we should not cross this ethical line, since it is likely to lead to a future of genetically modified "designer" babies.

Such a slide has already been seen with drugs and surgery. The ugly beginnings of a eugenic market are already visible in the US, where Ivy League student donor eggs are priced 10 times higher than those of working-class women. Genetic enhancement also risks dehumanising and commodifying relationships between children and their parents. These downstream consequences cannot be ignored in making the present decision.

Mitochondrial replacement techniques also create significant epigenetic risks to the prospective child. Prevention of mitochondrial disease can be more safely...