I've read some lines from wikipdeia and it didn't really help. So... Here I am.

My alien species has three genders and all of them are active in the act of reproduction. In doing so, I would like to rely on a human-like genetics, because then I have to explain less.

So far I'll have two of them vomiting inside the thirds throat. Three months later, the third gives birth to a child with a genetic mix between the three.

Now I want to know how the process of the "baby" beeing made out of these three components would work.

  • Does the DNA need a different structure?
  • What kind of chromosomes are needed?
  • How many of them?
  • Am I even asking the right questions?

Please give me some advice how I should formulate my problem. I'll be happy to ask the question again in a different way.

  • $\begingroup$ I don't think you are asking the right questions, as DNA would not have to change to account for multiple gene sets. Plants have more than 2 sets - unlike humans. It also makes them more resistent to radiation. The structure of DNA is irrelevant to this problem. DNA can support asexual as well as sexual reproduction. Why not one with multiple partners? $\endgroup$ Jul 16, 2018 at 7:06
  • $\begingroup$ Welcome to WorldBuilding.SE! You might be interested in some of our existing questions about species with three genders, such as Gender ratio in a three gender system and How to handle a tri-gendered race If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$
    – Secespitus
    Jul 16, 2018 at 7:08
  • $\begingroup$ @Aify, I think that one is more focused on the cultural aspect, while this one on the "technicalities" of the 3 genders reproduction. $\endgroup$
    – L.Dutch
    Jul 16, 2018 at 8:08
  • $\begingroup$ The short story "Gold" by Isaac Asimov might of some help here, since a good chunk of it deals with a tri-gendered species. en.wikipedia.org/wiki/Gold_(short_story) $\endgroup$
    – ironduke97
    Jul 16, 2018 at 8:17
  • $\begingroup$ Just as a little tip for the future: it is recommended to wait at least 24 hours before accepting an answer, as there are people from all over the globe active on Worldbuilding.SE. Some of these might feel that there is no need to further interact with your question when they see that you already found a solution that works for you, leading to less answers/improvements for answers. Waiting may increase the amount and quality of answers you get. Of course it's completely up to you whether you want to accept something or not and if so when and what. Just a tip for the future. $\endgroup$
    – Secespitus
    Jul 16, 2018 at 9:23

1 Answer 1


We human carry two types of DNA: the nuclear DNA, contained in the nucleus of our cells and made through the merging of our parent's halves, and the mitochondrial DNA, contained in the mitochondria, which is inherited only from the mother's side.

In your case you could have parents A and B provide their respective share of nuclear DNA, while parent C would provide the nucleus-less cell where the nucleus resulting from A+B would be hosted and where the mitochondria from parent C would also be present.

Since the reproductive system is not connected to the digestive system, your system of mating seems quite odd (regardless of how does it even sound like).

Probably having parent A and B provide their genetic contribute to C via our "standard" method would suffice your scope. Maybe just add two mating channels, so you can prevent mixing up of the individual contributions. You don't need to change DNA, and the amount of chromosome is irrelevant for the sake of the question.