A couple years ago, a couple from Washington had concerns when they found out that their son’s blood type wasn’t a match to either of theirs, especially since they had the child with help from a fertility clinic. So, they took a paternity test, which the father failed, meaning that genetically, he wasn’t his son’s father. After a genetic ancestry test, they discovered that genetically, the man was actually his son’s uncle.

There was nothing extramarital going on here: It turns out that the man is what is known as a “human chimera,” because he absorbed his dead twin’s DNA in the womb and now has extra genes (via The Independent). So now, the genes found in his saliva are different than the ones found in his sperm. This means that technically, the child’s father is actually the man’s twin, who was never born.[/nerdist_section]Chimeras — simply put, a person with the genes of more than one person — might seem like an oddity, but they might not be as rare as we would think. As the New York Times notes, Canadian scientists performed autopsies on the brains of 59 women in 2012, and found neurons with Y chromosomes in 63 percent of them, which they believe “developed from cells originating in their sons.”

More recently, scientists created human-pig “chimera embryos,” as BBC reports, but don’t start thinking we’re on our way to human-animal hybrids: the embryo was “less than 0.001% human.” Either way, though, the science surrounding chimeras is interesting to think about.

Suppose you could make hybrid animals, though: Since we’re in the Halloween season of spooky and bizarre things, what combinations would you create? Let us know what you think in the comments below!

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