I confidently predict that people will still be having sex in 20 to 40 years’ time, but they will be using sex to conceive their babies much less often. Two biomedical advances are going to change how humans reproduce: whole genome sequencing and stem cell technology.

For over 25 years now, some babies have been born after something called pre-implantation genetic diagnosis (PGD). Three- to five-day-old embryos have some of their cells removed and subjected to genetic testing. Parents and doctors then decide, based on the test results, which embryos to transfer into the womb in the hope of making a baby. Last year 3,000 to 4,000 babies were born in the US after PGD without any obvious safety problems.

PGD will soon get much better, becoming what I call “easy PGD.” Cheap whole genome sequencing is one reason. The first whole human genome was sequenced in 2003 at a cost of about £350m. Today, a whole human genome sequence costs around £1,000; in 20 to 40 years, it will be far less. Before, PGD was able to look at one or a handful of genetic traits; it can now look at an embryo’s whole genome and the futures that genome implies. That will make PGD much more useful to parents.

The big problem with PGD, though, has been that it requires in vitro fertilisation (IVF). Invented in the UK nearly 40 years ago, IVF has been a godsend for millions, but it has not been easy. Harvesting eggs from a woman’s ovaries is expensive, uncomfortable, and somewhat risky (life is unfair – sperm collection usually has none of those problems).

Stem cell technologies will bypass egg harvesting. Instead we will take a woman’s skin cells; turn them into so-called “induced pluripotent stem cells” (cells very similar to the famous embryonic stem cells but made from living people); turn those cells into eggs, and mature the eggs in the lab. This would not only greatly reduce the cost, discomfort and risk of IVF, but would allow each woman reliably to produce hundreds of eggs (or more). It already has worked in mice and the first steps have been taken with humans.

The result will be easy PGD. A couple who wants children will visit a clinic – he will leave a sperm sample; she will leave a skin sample. A week or two later, the prospective parents will receive information on 100 embryos created from their cells, telling them what the embryos’ genomes predict about their future. Prospective parents will then be asked what they want to be told about each embryo – serious early onset genetic diseases, other diseases, cosmetic traits, behaviours, and, easiest but important to many: gender. Then they will select which embryos to move into the womb for possible pregnancy and birth.

Easy PGD will not produce super-babies. Genes aren’t that important. But it will produce children who have little or no chance of some serious diseases; better than normal chances of avoiding other diseases; preferred hair or eye colours; slightly better chances of high maths, sports, or musical ability; and who are of the parents’ preferred sex. The health and behaviour differences are likely to be about the same as the average differences between being born to rich parents and poor parents – not enormous, but not trivial.

These would not be designer babies. Parents could only select from the genetic traits they carry. New gene-editing technologies such as CRISPR may eventually make it possible to edit embryos, but easy PGD, and its selected embryos, will be safe, effective, and available years sooner. I suspect selection also will be more attractive to those many parents who want children “like themselves” – but like the best of themselves, not the worst.

It will be attractive to those many parents who want children like themselves – but like the best, not the worst

To many people this sounds like fiction. And of course, it does raise difficult and important questions – from safety, fairness, and coercion, to family structures and whether it’s “just plain wrong”.

Could it really happen? I think so. Many parents will want it, if only to avoid the 1-2% risk of having a child with a severe early genetic disease. Health systems will find it cost-effective to no longer have to provide care for children who are born sick. Clinics will want the business, and governments will be reluctant to interfere in parental choice – at least in some places.

Its reception will vary from country to country. I expect the US, much of east Asia, Australia, and some other countries to allow or even encourage easy PGD. Germany and Italy, probably not. The UK will be interesting. As opposed to America’s wild west, the UK has the Human Fertilisation and Embryology Authority, which has allowed, with limits, new reproductive technologies based on both safety and perceived moral concerns. What will it do with easy PGD?

Before long many countries – as well as individual couples – will have to make these choices. Cheap sequencing and stem cell technologies are inevitable, driven mainly by non-reproductive uses. To choose wisely, for ourselves and for our countries, we all need to learn more about this burgeoning of genetic choice, its likely paths and consequences. The time to begin is now.