How Does Biotech Gene Inheritance Work in RimWorld

This guide will explain how gene inheritance works in RimWorld. The results on this guide is done in the dev mode of the game and no code was viewed during the process.

Basic Information

There are three types of genes.

  • Germline genes – your all-natural home-grown inheritable genes.
  • Xenogenes – your lab created and injected genes.
  • Archite genes – special high-tech genes that are very powerful.

There are 3 numbers attributed to a gene.

  • Complexity – a value that affects how many genes can be assembled into a gene injector.
  • Metabolic Efficiency(ME) – increases/decreases hunger rate for pawns. (Abbreviated as ME here)
  • Archite Capsules – a rare resource needed for implantation. Get from traders or quests.

Genes considered beneficial will usually reduce ME, increasing the hunger rate. While genes considered detrimental will increase ME, reducing the hunger rate. Archite genes will have high complexity with 0 ME change. The exception is Archite Metabolism, this gives +6 ME at the cost of 3 Archite Capsules.

Gene Inheritance

This section is about putting the genes you want on your pawns whether pureblood or hybrid. Testing for this section was done using the ‘Extract ovum for IVF’ operation, NOT pregnancy.

You can check the gene inheritance of a harvested ovum after it has been fertilized. It will show all potential genes it has inherited.

A germline gene is inherited if:

  • Both parents have the gene. (guaranteed)
  • One parent has the gene. (not guaranteed, Reddit comments estimate a 25% chance)

If there are multiple genes for skin tone/hair color etc, one will be picked after gestation. The unchosen options will be grayed out, yet still inheritable for future generations. Sometimes an unseen color gene is created after gestation. Currently unsure if it’s due to me using dev. mode to add color genes or just random chance.

If two pawns of the same Xenotype create a child together, the child will inherit the Xenotype of the parents. If the parents do NOT share the same Xenotype, the child will be a hybrid.

Gene Implanter

The Gene Implanter gene is an Archite gene that injects all of a pawn’s genes into another pawn. There is some variability in its function.

What will get transferred:

  • Xenotype – The pawns Xenotype will now read as the source pawns Xenotype.
  • Germline genes – the new genes will take priority and null out opposite/conflicting new genes from the previous Xenotype of the destination pawn.
  • Xenogenes – same as Germline genes but will take priority over Germline genes.
  • Archite genes – will get transferred ONLY if under the Xenogene category. If an Archite gene is in the Germline genes category, will NOT get transferred.

Could be used for custom Sanguophage playthroughs where one propagates genes to the others and only the original has the power of bestowal. (Put Gene Implanter as a germline gene, labeled as an endogene in dev mode)

Does not appear to need archite capsules to transfer Archite genes.

Vat Grown, IVF, Natural Pregnancy

I have only experimented in dev. mode using IVF Ovums with growth vats. I have not tested if everything works the same using natural pregnancies. It is possible the rates of inheriting a parent’s genes are different when carried to term by a parent but I doubt it really matters currently.

Testing Methods

Removing the Hediffs that appear to prevent immediate gene implantation, ovum extraction, etc. Leaving the anesthetic on prevents the subject from wandering off, thus speeding up the process. Used pawns with correct gene set to fertilize Ovums. The sample size of Ovums for each conclusion is 10. It is possible for my data size to be too small, but it should be reliable enough since this is just a game. Now we can add eugenics to the list of Rimworld memes.

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