I am working on a world inspired by witcher where humans and animal like race live together. would for example, human crossbreeding with water dwelling humanoid cause something like mermaid syndrome? but human crossbreeding with different human ethnicities would be same as in our world.

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2 Answers 2


Up to your Imagination

Humanimals are not real. Since they are not real you get to decide how they work. In particular you get to decide how their children with pure humans deal with traits from both parents. If you want the Birdman and man-man child to have brittle bones that is up to you. If you want normal human bones that is also fine.


One has to wonder if human's bred with animals before hand to get these animal humans -.-

As said above, its up to your imagination. That said, humans have a peculiarly high number of genetic defects and the cause is actually the opposite of varied breeding. Long ago there were multiple cousin species of humans such as the Neanderthals and Denisovans - then some catastrophe hit and wiped out most life on Earth. After that extinction event, there were so few humans left that the inevitable interbreeding of close relatives led to an increase of birth defects across the entirety of the (reset) human family tree. Thus, if humans and animal people can interbreed it would probably lead to healthier genetics - but not necessarily babies with an "optimized" physiology.

As the son of a dentist let me throw an odd fact at you. People who breed within their own ethnic group will have children with very few teeth problems. People who breed across ethnic groups have children with higher probabilities of teeth problems. This happens because different ethnic groups have different jaw shapes and when a child inherits an averaged upper and lower jaw between two different parents, the resulting jaws aren't always viable corresponding shapes.

There are also odd cases where breeding different inter-breedable species (different genus, same species) turns off inhibitor genes -genes which prevent options within a creatures genes from ever activating. Breed a female lion with a male tiger and nothing spectacular happens. Breed a male lion with a female tiger and you get a liger. Lions and tigers have inhibitor genes which cap their growth size, for some reason the exact combo of a male lion nd a female tiger disables that inhibitor gene resulting in a truly massive cat. Whether a human and fox person having a child twice their size with decreased life span is a birth defect is up to you however.

Tldr: Less defects but possibly unexpectedly wonky body proportions.

  • $\begingroup$ I first thought you might mean teeth problem as something like more caries, you are speaking about jaw structure here - a critical thing! $\endgroup$
    – Trish
    May 11, 2022 at 10:37

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