Okay, so, if Princess Twilight and Pony Sunset were to... do a magic thing, I guess? that resulted in a child that carried both of their genes, are we to assume that this would be a unicorn or an alicorn? Assuming that Sunset is still a unicorn.
I mean, like, what's the general consensus on this? Or is it up to interpretation? Which is preferred?

5402581 Alicornism is usually not perceived as being hereditary. Although the season 6 premier seems to negate that, the general consensus is that you have to earn the right to being an alicorn, such as how Twilight earned it. So no, the foal would probably not genetically be an alicorn, unless heavy magic was involved.

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Batpony, clearly.

5402587 Yeah, that's what I was thinking as well. After all, even if Flurryheart has outright annihilated many a headcanon, starting as a unicorn leaves more room for development. So here's a better question: would the kid still carry the title of "princess", alicorn or otherwise? After all Prince Blueblood seems to have no issue with carrying around a royal title in spite of his decisively glaring lack of wings.

5402609 Truly, this is the truest sentiment ever typed in these Faust blessed forums. I believe we should all look upon the wisdom it brings us and kneel before it... Twilight and Sunset's kid would be a thestral.
I want to see a story about that now.

5402646 Royalty would be passed down in a hierarchical fashion, making the foal a Prince/Princess. This is regardless of species.

For my thought, an alicorn's genes would be dominant, but it's everyone's decision right? But, I actually need to get on more hands on research on that.

A lot of headcanons I see are that Alicorn foals are possible, but extremely rare.

5402581 well first off the offspring would be female 100% of the time unless the spell changes the targets chromosomes, as for will it be an alicorn it depends on whether or not the genes responsible for alicornhood are recessive or dominant also a further layer of complexity is added when a father's genes are more dominant than the mother's so for example let's say twi is the pseudo father and assume that alicorn genes are dominant and for argument's sake let's also add in the variable that sunset shimmer is really Celestia's daughter meaning she would be carrying recessive alicorn genes. an offspring resulting from the two would have a 50-60% chance of being an alicorn if sunset lacked the recessive genes and or is the father the chance reduces to 25% if both parents were alicorns the chances of having an alicorn as a child increases to 75-85% and that increases to 100% if both parents are pedigreed as in having alicorn only ancestors not to be confused with thoroughbreed a horsebreed known to be inbred specifically for racing.

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I'm gonna say, unicorn. Since an alicorn birth had never been seen before flurry heart, I think that was for a reason, I don't think it would happen again.

5403085 Holy crap, I should have paid more attention in biology. Thanks! Now I have a scientific explanation.

5403226 heh well the Internet can help you as well.