Kikazaru and Protogon have been fierce rivals in the designer baby industry/artificial wombs since time and memorial, but Kikazaru is looking to finally best its rival by introducing a new scheme: designing babies so same sex couples (biologically speaking since identity makes this a bit murky) can have a child of 'their' own.

Is it possible to engineer a embryo with genes of both partners (selected either by choice or selected by rng)? Would it be possible for say both two males, females, or would this service only be able to be provided to one such pairing? What issues might Kikazaru possibly run into with this scheme?

Ex: would chromosomes be an issue in any way or would it simply be: the child is going to be this sex without special intervention.

Note: While Kikazaru has experience in editing genes to change genotypes for things like: eye color, hair, general characteristics, etc. This (in my mind) would be uncharted territory.

They also have experience with gene editing to combat hereditary diseases if that could possibly be an issue (I'd be interested to hear if it would be).

  • $\begingroup$ While I definitely have moral reservations on engineering babies, it is becoming possible and scientists have made sperm cells from male mouse skin cells. It's also a potential reality within our lives such a thing could be possible. google.com/amp/s/amp.theguardian.com/science/2018/oct/14/… . So the idea of it being possible is not far fetched. I havem't done a ton of research so I don't know of any further complications, probably handwaved by tech level anyways, but it's based in a sound principle. $\endgroup$
    – mVitus
    Mar 11, 2019 at 4:01
  • $\begingroup$ @mVitus I'm neutral on the issue itself. But in my universe I knew someone was going to cash in on this market. Especially if it's legal (with limitations of course to prevent ostracism, horrible defects, etc) $\endgroup$ Mar 11, 2019 at 4:07
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    $\begingroup$ Two-Father Babies Could Soon Be Possible, With No Egg Donor Required - the first google result when you look for it. $\endgroup$ Mar 11, 2019 at 4:11
  • $\begingroup$ Also if you feel like engineering eggs, also done. newscientist.com/article/… $\endgroup$
    – Borgh
    Mar 11, 2019 at 11:04
  • $\begingroup$ Think alittle further and you can come to a world where only females exist, because they live longer and healthier. $\endgroup$ Mar 11, 2019 at 14:38

4 Answers 4


It would definitely be possible for male-male couples. Female-female couples are much more challenging.

Here are the embryo generation procedures for same-sex couples (the embryos afterwards are either implanted in the womb of one of the parents, a surrogate, or an artificial gestator):

Male-Male Couple → Male or female child:

This one is easy, since there's an X chromosome, a Y chromosome and plenty of sperm. I never want to type those last three words again.

Both parents provide sperm, which is centrifuged and separated by weight (the X chromosome is heavier than Y). An X sperm has its nucleus removed and inserted into an enucleated egg cell, which is then fertilized with an X or Y sperm from the other parent (they can choose or leave it to chance).

Alternatively, you could use stem cell technology to program a man's germ cells to produce eggs. The DNA is produced the same way for eggs and sperm, so men have all the necessary hardware to, with a little tweaking, produce viable human egg cells.

Female-Female Couple → Female child:

The egg cell is comparatively easy to get, just take one from the ovary surgically. The sperm cell is a different story. Unlike in the case of the male-male couple, we can't necessarily replace the nucleus of the sperm cell with the nucleus of a female egg cell. The problem is that the nucleus of an egg cell is several times larger than the sperm cell. It would be like trying to put an egg into a grape: surgically impossible.

Also, sperm cells are really fragile. When you have 1 egg and a million sperm cells, the egg has to be really durable, but it doesn't matter if a sperm cell malfunctions. Sperm cells often have defects like 2 tails or 2 heads, both of which prevent the sperm from reaching the egg. Unfortunately for Kikazaru, this means that trying to replace the nucleus of a sperm cell (a process that involves putting a huge hole in the cell membrane) will probably make the sperm non-viable.

We also can't get the woman to produce sperm by manipulating cell specialization, because the woman's germ cells (the cells that produce eggs and sperm) become inactive after birth, so adult women can't produce new eggs at all, let alone sperm.

To get around this, we would have to remove the DNA from the female and directly put it into the sperm cell. It can't be from any cell in the mother – otherwise the child would be half-cloned from the mother. The DNA has to be taken from the germline, after recombination (the process that shuffles the DNA from 46 chromosomes to produce the 23 that go into the egg or sperm). Typically, to get DNA from a cell intact, we would find cells in metaphase, when the DNA is grouped into neat chromosomes (with chromosomes, you can count how many there are under the microscope to make sure you have them all). But female human germ cells turn into eggs before birth, and stop dividing – they never enter metaphase.

So you have to take the germline DNA in interphase, when it's grouped into a structure called chromatin, which is loose, tangled and messy. It also tends to fill the space it's given, so it will be the same size as the egg nucleus. So you would grab all of the DNA, then squeeze it into the sperm, trying not to make it explode in the process. This is super messy, so you'd have to repeat it over and over, and women have a limited amount of egg cells, so you'd have a good chance of rendering the woman infertile while failing to produce a child.

A possible solution would be Artificial Gene Synthesis, also known as DNA printing. This technique allows researchers to synthesize DNA strands of any sequence they want. Currently this works by creating random DNA until the right sequence is found, so it takes longer the larger the DNA you want to create. In the future, though, we might be able to produce entire human genomes in the lab (I'm guessing Kikazaru and Protogon already can do this as part of the designer baby process).

The lab would sequence the mother's DNA (read all of the genes) and then reprint them into a germ cell donated from a man, which would then recombine the chromosomes and develop into 4 sperm cells by meiosis. Then, one of the sperm would be sucked into a pipette and forcibly shoved at the egg, which it would hopefully fertilize (if it doesn't, rinse and repeat).

Female-Female Couple → Male child:

Same challenges as above, with the addition of the Y chromosome problem. To make a boy, you need a Y chromosome. A same-sex female couple has 4 X chromosomes between them. To get this to work, you'd need a male Y chromosome donor, so a small part of the child's DNA would come from a third 'parent.' Luckily, Y chromosomes aren't really that important. Their DNA consists of 'Be a dude' + a few random genes, including the gene for hairy ears (for some reason). So the DNA of a healthy, hairless-eared male would be sequenced and would replace the X chromosome in the Artificial Gene Synthesis process described above.

Bonus: Babies with more than two polyamorous parents!

If we're running everything through sequencing and gene synthesis, we can just treat DNA as data. This means that you could have a child with yourself, using an algorithm that finds the healthiest recombination of your own DNA to avoid inbreeding (like cloning with a little bonus shuffling). You could have a kid with 10 other people, where you each contribute a couple of chromosomes, and the algorithm does the rest.

And much, much more!

You could have a child with a dead historical figure whose genes have been extracted from their hair, or with a celebrity. There would be crowds of people trying to get DNA samples of famous people to sell on the DNA black market. Give birth to a baby clone of Tom Cruise for just $5000!

Who said anything about human-only DNA? Make your baby able to photosynthesize! Make them digest cellulose! Have permanently blue hair! Take your pick.

Yeah, designer babies are pretty freaky. Once you have the tech to make a male child of female parents, you can totally play god with humans.

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    $\begingroup$ oh the doors you just opened in my mind with the celebrity babies. Both Protogon and Kikazaru are going to make fortunes off of human vanity. Also I do wonder what being a uni baby would be like. $\endgroup$ Mar 11, 2019 at 17:42
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    $\begingroup$ @CelestialDragonEmperor Having single parent – literally. And yeah, designer babies is pretty much the height of human vanity. $\endgroup$ Mar 11, 2019 at 18:59
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    $\begingroup$ sorry I meant like the social impact of unibabies. The likely discrimination. $\endgroup$ Mar 11, 2019 at 19:41
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    $\begingroup$ @CelestialDragonEmperor Well, in a society progressive enough to legalize all of this, I don't think it would be too harsh. Also, your parent would be able to give you pretty solid advice for life, since you have such similar bodies and development curves. $\endgroup$ Mar 11, 2019 at 20:04
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    $\begingroup$ I can just imagine a story about the kind of person that would want a child just like them made from just them $\endgroup$
    – coagmano
    Mar 12, 2019 at 5:25

In principle one could devise the following way of working:

  • take the reproductory cell from partner A
  • take the reproductory cell from partner B
  • if neither A or B is an egg, take an egg from a donor C, or create a synthetic one
  • join genetic material from A and B (in C if needed) and stimulate fusion

However, in humans females are carriers of XX chromosomes, while males are XY. So, when you pair two males you have the possibility of pairing a YY embryo, which is non vital. Therefore you need to find a way to filter X from Y, or accept a higher mortality rate in male-male couples.

  • $\begingroup$ IIRC correctly it is possible to separate X sperm from Y sperm by size or mass. $\endgroup$ Mar 11, 2019 at 4:36
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    $\begingroup$ The X chromosome is carrying a lot of vital genes, just like the 22 others. YY will never make it even to fetus state. $\endgroup$
    – Karl
    Mar 11, 2019 at 6:43
  • $\begingroup$ @Karl, changed fetus to embryo. $\endgroup$
    – L.Dutch
    Mar 11, 2019 at 10:37

With two males you could take the X chromosome from one and mix with the Y chromosome of the other to give a baby boy OR you could take both X chromosomes to make a baby girl. (Note, as this is being done artificially, you wouldn't create a YY)

With two females however, there is no Y chromosome to make a male embryo, so you would have to work out some other way of engineering that Y chromosome which isn't possible with current real world science (eg modifying an X into a Y or transfer an X into existing Y chromosome would delve into SF).

This is assuming you've already sorted some way to create an egg/embryo from just chromosomes (ie you can graft the DNA into an existing fertilised egg, or create an unfertilised egg plus sperm with specific mRNA(?))

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    $\begingroup$ The X and Y chromosomes contain completely different genes, so you can't convert an X chromosome into a Y chromosome exactly, but it is theoretically possible to transfer the SRY gene (the primary gene responsible for masculinization) to the X chromosome, which would induce XX male syndrome. Bear in mind, however, that is a type of intersex condition, so the resulting child will be infertile (without artificial assistance on par with the techniques used to create them) and the degree of masculinization is variable. $\endgroup$
    – Dan Bryant
    Mar 11, 2019 at 13:55
  • $\begingroup$ I think for females, you should just say, that since Women are XX, you can only make girls from their genes, or you will need a y donor. x -> y is the realm of fiction. $\endgroup$ Mar 11, 2019 at 14:14



One way that chimeras can happen naturally in humans is that a fetus can absorb its twin. This can occur with fraternal twins, if one embryo dies very early in pregnancy, and some of its cells are "absorbed" by the other twin. The remaining fetus will have two sets of cells, its own original set, plus the one from its twin.

This is simple compared to trying to make a baby out of 2 sperm or trying to make meiosis obey your commands.

1: Make a somatic clone of each partner.

2: Then at an early stage in development, merge the cells.

The resulting embryo will be a mix of the two partners, just as one type of chimera is a mix of two twins.

Bonus 1: This sidesteps recessive genes issues and the possibility that a child of two parents who are both heterozygotes might be homozygous for a detrimental recessive.

Bonus 2: There is no reason offspring made in this way might not be made of 3 or more individuals, all contributing cells and genes to the final chimera.

Downside: The chimera's own gametes will be those of only one contributing "parent", not a mix of them all.


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