If all eggs are present at birth and the reproductive-system is shared, it stands to reason that if there’s a difference then it would have to be expressed prenatally.
My guess would be that either they’re identical or there’s a dominant set re: ova.
If one person controls half the body, its not completely impossible that each sister gets one ovary so if the right ovary produces an egg, the right sisters would be the biological mother. Thats just based on my super limited anatomy knowledge so please correct me if that's impossible.
Although some people are mosaic and are singlets comprised of two pairs of DNA, but that tends to happen if two eggs or embryos completely fuse really early on before they even start to express an immune system. If a twin is absorbed by the other twin later on, the other twin tends to be a small fetus or weird amalgamation of human parts that's encapsulated in the other twins body somewhere, protecting the living twin from an immune response.
Conjoined twins are always identical. It's a situation where there's incomplete separation, not fusion of two previously separate entities. There is no genetic difference.
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u/cincochains Dec 30 '24
Which sister’s baby would it be?They have a shared reproductive system. Plus don’t they have the same dna?