Nobody is saying they aren't Americans. They are naturalized Americans, full citizens as much as anybody else. The only thing they aren't, is qualified to be president or VP.
I really doubt that any of the founders even considered women in the military serving overseas. Diplomats may have brought family, but that was rare also and there weren't diplomats sent to every little country in the world.
Finally for the fools who keep asking about boarder jumpers who drop a kid in San Diego, both parents must be American citizens to be natural born. I never thought that Obama was eligible, and still do not.
2 American citizen parents, born in the US of A, that's what they taught me half a century ago in grade school and that is what it means.