No matter how much opprobrium is thrown at the idea of ‘three parent babies’ (TPBs) by purists, the method is surely here to stay. The first TPB procedure was carried out in Mexico earlier this year — where there are no laws against it — and at least one is planned in this country in 2017 — where the practice was legalised last year.
The first TPBs will be that of mitochondrial replacement in cases where females have inherited faulty mitochondria which can lead to serious diseases in later life. Mitochondria lie outside the DNA nucleus in our body cells, have their own much smaller packet of genes and are inherited only through the female line. A faulty line can only be extinguished if a mother has only boys.
The bulk of a person’s DNA is totally unaffected by TPB but the time is closely coming when another procedure called CrispR, or gene-editing, will be used to extract faulty genes and replace them with good ones. As with TPB in advanced countries, gene-editing will probably first take place in countries where their governments have been slow to legislate or are ideologically opposed to it.
Curiosity and challenge will be impossible to resist in the case of some of the leading exponents. Due to the complexity of genetic permutations, we’ll never have ‘designer babies’ as popularly understood but geneticists will be more than a millimetre or two towards them in the next few hundred years.