Guy Gardener wrote:
Why would they pick a no one to be the doner?
They probably did tests on a large number of orphans (that no one would miss if things went awry, hence why they'd pick one), and Sarah just happened to meet all the prerequisites they had for a donor.
It's the fact that she had a kid of her own and none of the other North American clones had any idea she existed that's the big indicator. Crazy psycho chick also seems to think there's an original donor.