Re: Re. Chimeras
Mosaicism is different to microchimerism. "Mosaicism" or plain chimerism is where two zygotes have fused in utero and organs develop with differing genotypes: you can literally end up with one arm with one genotype and the other arm with a different one, or with two different blood types; the case you're referring to (Lydia Fairchild) was an example of this. Microchimerism is where there are a few stray cells with a different source; mothers, for example, often have cell lines from their children lodged in their body or floating in their blood.
And. for the record, I think we can rule out both. Spitting in a test tube or swabbing a cheek wouldn't spot microchimerism. And even if the experts hadn't looked at the twins' DNA, what are the chance of two eggs being in the womb, one of which splits into two foetuses and then one of these foetuses fuses with the fraternal egg in such a way that the surviving children look identical but have different saliva glands?
Biting the hand that feeds IT
