Here's a wacky thing: the plural form of someone else is actually someone's else
Ah, I can see the reason for your disclaimer about not having good grammar. "Someone else's" isn't plural, it's possessive! Still an interesting fact though.. does it mean the possessive form of someone else is someone's else? Looks pretty wrong to me...
The fact that the genes are identical does not mean they're of the same origin.
Actually, if the genes are identical in terms of nucleotide sequence then it is absolutely irrefutable that they are of the same origin. Even genes that are evolutionarily conserved vary in sequence between members of the same genus, let alone organisms from completely different kingdoms of life.
What is algebra, exactly? Is it one of those three-cornered things? -- J.M. Barrie