A degree of caution, even scepticism, is a healthy thing so far as scientific advances are concerned. So it is with so-called “three-parent babies”, whereby a DNA of a third party can be used to prevent painful and fatal inherited diseases in babies.

The technique has been around in one form or other for some decades, but it has only now received the moral and legal backing of the Human Fertilisation and Embryology Authority (HFEA). They have subjected the new breakthrough to the most rigorous examination, both in terms of its medical and psychological effects, and sanctioned it for use in the UK. The NHS will treat about two dozen women next year, each case to be separately approved and licensed after consideration by the HFEA.

It is unalloyed good news for the simple reason that it will save lives and relieve suffering with no discernible risk to the health of the patient or the wider community. This is where mitochondrial replacement therapy (MRT) differs from, say, genetically modified crops, where the effects of the wider environment are much harder to detect and prepare for.

While respecting their moral and religious standpoint, to listen to some of the more hysterical reaction from the critics of this scientific breakthrough you might think that the authorities had given the green light to three-headed babies.

“Playing God” is the usual charge, and yet almost all modern medicine falls into this category because it involves intervention in some divine plan, if you are theist, or in the natural order of things. The progress of cancer, for example, is interrupted by doctors “playing God” to improve the lives of their fellow humans – and yet that is not considered in the same light as MRT.

The point about MRT is that it is not a compulsory treatment and nobody has to undergo it if it runs against their personal convictions. It is fair to say that the wider community does have to create some sort of framework of rules for morally-charged medical intervention such as termination of pregnancy and, indeed, genetic intervention, but the development of MRT has taken place very cautiously and safely within that framework of law.

In an imperfect world, then, the arrival of MRT as a mainstream (albeit highly advanced) treatment available on the NHS to those with a proven need, but not necessarily the financial resources to allow them to obtain it privately, is the best possible news for many families this Christmas. It is a celebration of what can be achieved by the partnership of medical research, moral guidance and the ability of today’s National Health Service to deliver treatments that would have seemed science fiction when it was first founded.