Designer Babies, IVF and Embryo Screening: Ethics for Medicine Interviews

Designer babies ethics is mostly an argument about something that does not exist. UK law lets IVF embryos be screened for serious inherited conditions, and for a tissue match to save a sick sibling. Choosing intelligence, height or appearance is unlawful here, and selection can only pick between embryos a couple has already made.

I am Dr Akash Gandhi, an NHS GP who has been preparing applicants at TheUKCATPeople since 2012. This topic sorts candidates fast, because the popular version of it is simply wrong and a panel can hear that in about fifteen seconds. Our guide to answering medical ethics interview questions gives you the structure. What follows goes inside it.

What people actually mean by a designer baby

A designer baby, in the sense the phrase suggests, does not exist anywhere. Embryo screening chooses between embryos a couple has already created. It writes nothing new into them, so it is bounded by what those two genomes can produce between them. That one point does most of the work in this station, and almost nobody makes it.

• Selection is not design. A clinic can rank the ten embryos in front of it. It cannot invent an eleventh, and if neither parent carries a variant, no test will find it.
• Complex traits do not behave like that. Height, intelligence and temperament involve thousands of variants of tiny effect, plus everything after birth. A perfect test would nudge the odds, not choose an outcome.
• Screening for traits is not lawful here anyway. Testing embryos against risk scores is called PGT-P, and the regulator says it is unlawful in the UK and unsupported by evidence.
• Editing is a separate argument. Rewriting DNA rather than choosing between embryos has its own law, and belongs to the gene editing debate.

When I run mock interviews, what costs marks is rarely a wrong date. It is the candidate who talks about ordering features from a list.

Key Takeaway: Selection can only choose between embryos two people have already made, so designing a baby describes a technology nobody has.

How embryo screening works, and what the UK allows

Embryo screening is only possible through IVF, and here it is licensed condition by condition by the Human Fertilisation and Embryology Authority, the HFEA.

• Collection and culture. Injections mature several eggs at once, which are collected under sedation, fertilised in the laboratory and grown on for about five days.
• Biopsy. A few cells are taken from each embryo’s outer layer, the part that would form the placenta, and the embryos frozen while those cells are tested.
• Transfer. One unaffected embryo is thawed and transferred. The rest are stored, donated or allowed to perish, which is part of why some people object.

The table is most of what you need. The interesting line runs between the tests the regulator has approved and the one it has ruled out entirely.

Over 2,000 conditions have been approved for PGT-M, and a clinic wanting anything else has to apply to the HFEA. The criterion is a significant risk of a serious condition, so the UK has no list of banned traits. It has a list of permitted conditions, and everything else is off by default.

None of it is evenly available. Only 28% of UK IVF cycles were NHS funded in 2024, and the criteria vary by area, which is the postcode lottery argument and a question of justice: a technology only wealthy families can reach raises different questions.

Key Takeaway: The UK does not ban traits, it approves conditions, and that inversion is the most useful thing to know about how this is regulated.

Saviour siblings: what Hashmi and Whitaker actually decided

A saviour sibling is a child conceived by IVF and selected partly because their tissue matches a seriously ill brother or sister, so that cord blood or bone marrow can be donated. Two British families asked the HFEA for nearly the same thing within a year and got opposite answers.

The case: the Hashmis. Their son Zain had beta thalassaemia, inherited from both parents, so any future pregnancy carried the same risk. In December 2001 the HFEA decided it could permit tissue typing alongside the screening those embryos needed anyway.

The case: the Whitakers. Their son Charlie had Diamond Blackfan anaemia, which in his case had not been inherited, so their embryos were not at risk. In August 2002 the HFEA refused: with no disease to screen for, a tissue match would be the only reason to test.

The distinction was procedural rather than compassionate, and it did not last. In July 2004 the HFEA allowed tissue typing on its own, and the House of Lords confirmed in April 2005 that it had the power to license it. The Whitakers had gone to Chicago, where their son James was born in 2003; Charlie had the transplant in 2004 and was reported the next year to be effectively cured. It remains a rare treatment.

• The donor child cannot consent to existing. Nor can any child, so the objection is weaker than it sounds. What they can be asked about later is further donation, which is consent and Gillick competence territory.
• Cord blood is not bone marrow. Collecting cord blood harms nobody. A marrow harvest under anaesthetic from a young child who has not agreed is a real non-maleficence problem, and the law does not permit taking a whole organ from a child this way.
• Conceived for a reason is not the same as used. Being wanted for two reasons is not obviously worse than for one. But such a family is not choosing freely, and beneficence towards the sick child can swamp everything else, as disputes like Charlie Gard show.

Key Takeaway: The regulator drew its line at whether the embryos needed testing anyway, then moved that line within two years, which is ethics catching up with practice.

The screening test that is popular and unproven

PGT-A checks whether an embryo has the normal number of chromosomes, and it is one of the most widely sold optional extras in UK fertility treatment despite a poor evidence base.

The HFEA rates add-ons with a traffic light system, from green for high quality evidence of benefit, through black for no effect, to red for a safety concern or a possible reduction in effectiveness. PGT-A is rated red for improving the chance of having a baby in most patients, and grey, meaning insufficient evidence, in older patients.

• It removes options rather than adding them. PGT-A is a filter. It cuts the number of embryos available for transfer and can lengthen the time to conception.
• An abnormal result is not always right. An embryo can be a patchwork of normal and abnormal cells, so a biopsy of a few outer cells can lead to a viable embryo being discarded.
• It is not useless. The same regulator rates it green for reducing miscarriage, so it changes what happens without reliably changing whether a baby is born.

In general practice I see the other end of this. People come back from a private cycle holding a price list rather than a question about genetics, wanting to know which extras were worth paying for. Telling them a regulator publishes exactly that judgement, free, is often the most useful thing I say.

Key Takeaway: Naming one add-on that is popular and unproven shows a panel you understand evidence-based medicine rather than just the phrase.

Sex selection, and why the UK says no

You cannot choose your baby’s sex in the UK for social reasons. Sex may only be selected where it relates to the health of the resulting child, which means avoiding a serious condition affecting one sex, such as Duchenne muscular dystrophy or haemophilia. Note what the law regulates: not the testing, but preferring one embryo over another.

• For allowing it. Reproductive autonomy is a strong principle, no third party is obviously harmed by a family with two sons wanting a daughter, and wealthier people already travel abroad, so the ban mainly restricts everyone else.
• Against allowing it. Where son preference is strong, permitting choice has skewed sex ratios at population level. Discarding a healthy embryo because of its sex sits awkwardly with the claim that sex is not a defect. Family balancing is also hard to police.
• What the public said. When the HFEA reported on its consultation in November 2003, 80% of the 600 respondents did not want sex selection for non-medical reasons.

Key Takeaway: The UK ban is not a claim that sex selection always harms someone, it is a judgement that the harms are collective while the benefits are individual.

Is embryo screening eugenics?

Not in the historical sense, because no state is directing it and nobody is being forced. But the comparison deserves a proper answer rather than a brush-off, and part of the objection survives the obvious reply.

The history is closer to home than most candidates realise. The word eugenics was coined by Francis Galton in 1883, and the Eugenics Education Society was founded in London in 1907. The Mental Deficiency Act 1913 allowed people judged mentally defective to be segregated in institutions, though Parliament refused sterilisation, defeating a voluntary sterilisation bill in 1931 by 167 votes to 89 and rejecting the idea again in 1934 and 1937. Britain invented eugenics and never passed a compulsory sterilisation law. Germany did, from 1933, and that is largely what discredited the movement here.

• Why it is not eugenics. Three features made historical eugenics what it was: the state decided, individuals were coerced, and the goal was improving a population rather than helping a family. None applies to a couple choosing not to pass on Huntington’s disease.
• Why part of the objection survives. This is sometimes called liberal or backdoor eugenics. Thousands of private, well-meant decisions can still change who gets born, and no individual chose that aggregate. The state is not neutral either: it licenses the clinics, approves the conditions and sometimes pays.
• What a strong candidate does with it. Concede the aggregate point rather than fighting it, then say what would worry you. For me it is screening drifting from serious conditions towards traits, and the day declining a test starts to be treated as irresponsible.

Key Takeaway: The voluntary answer is right but incomplete, because a pattern nobody chose can still emerge from choices everybody made freely.

The disability rights objection, and choosing a trait on purpose

The strongest objection to embryo screening is not that it is unsafe. It is that it says something. If a society routinely screens out a condition, people living with that condition can reasonably hear a message about whether they were wanted.

This is neither fringe nor a strawman. When the Nuffield Council on Bioethics examined prenatal testing in 2017 it spoke to people living with Down’s syndrome and other genetic conditions, and its recommendations were restrictive: no testing for less significant conditions, carrier status, adult-onset conditions or non-medical features.

The reply worth giving is that a judgement about a condition is not a verdict on a person. That is reasonable, and incomplete, because the person on the receiving end is not thinking about a category either.

The sharper version of the question is not screening a condition out. It is choosing one in.

The case: in 2008, while Parliament debated what became the current law, the deaf couple Tomato Lichy and Paula Garfield objected publicly to a clause preventing them from choosing a deaf embryo. They treat deafness as a culture and a language rather than a defect. Some people with achondroplasia make the same argument.

UK law gives them a flat no. Because an embryo known to carry a serious condition must not be preferred to one that is not, selecting deliberately for deafness or achondroplasia is prohibited even though selecting against them is allowed. Somebody has to decide what counts as serious, and here that is a regulator rather than the parents. The same tension runs through the abortion debate.

Key Takeaway: Screening against a condition and screening for one are legally opposite in the UK, and saying why is the fastest way to show you have thought about this properly.

What interview questions could come up on this?

Likely questions

1. What do you understand by the term designer babies, and are they possible?
2. Should parents be allowed to screen embryos for genetic conditions?
3. What is a saviour sibling, and is it ethical to create one?
4. Should people be able to choose the sex of their child?
5. Is embryo screening a form of eugenics?
6. A friend says IVF clinics can now select embryos for intelligence. What would you say?
7. You are on work experience and a woman waiting for a fertility appointment asks whether the extra genetic test she has been offered is worth paying for. How do you respond?

Less likely questions (harder, but worth knowing)

1. Where would you draw the line between a serious condition and a trait?
2. A deaf couple want to choose a deaf embryo. On what grounds would you refuse them, and are those grounds consistent?
3. Who should decide which conditions can be screened for: parents, doctors, a regulator or Parliament?
4. If a screening test is popular with patients but unsupported by evidence, should clinics sell it?

Model answer: "Is embryo screening a form of eugenics?"

No, in the way the word is normally meant, but the comparison is doing useful work and I would not dismiss it.

Historical eugenics had three features. The state decided, people were coerced, and the aim was to improve a population rather than help a family. Britain went a long way down that road: the word was coined here in 1883 and Parliament debated sterilisation more than once. None of the three describes a couple who carry cystic fibrosis choosing an embryo that does not.

What survives is the aggregate. If enough families make the same private decision, the number of people born with a condition falls, and nobody chose that as a policy. The state is not outside it either, since it licenses the clinics and approves the conditions.

What would change my view is drift. The UK approves specific serious conditions and rules out testing embryos against risk scores for traits. If that moved, or if declining a test became something you were judged for, I would be far more uneasy.

Why this answer works:

• It defines the term before using it. Naming what made eugenics eugenics means the comparison can be tested rather than asserted.
• It concedes the strongest counter-argument. Giving the aggregate objection away early is more persuasive than defending against it.
• It uses one specific, current fact. Knowing the UK approves conditions and rules out polygenic testing shows reading, not opinion.
• It says what would change its mind. Naming drift as the trigger turns a position into reasoning, which is what the station marks.

Several hundred more sit in our medical school interview questions guide, with the wider set in our medicine interview hot topics guide, and our medicine interview tutoring runs mock MMI and panel interviews with feedback.

Key Takeaway: Practise this against a clock, because the eugenics question rewards a definition in the first fifteen seconds and punishes a warm-up.

The one line to take into the room

Embryo screening chooses between embryos that already exist, which is why it cannot design anybody. The live arguments are about who decides what counts as serious, and what happens when thousands of private choices add up. Get those two out early and everything else you know has somewhere to attach itself, including the four pillars.