Oh really?
Which "laws of citizenship in 1907," exactly?
The ones in place at the time of George Romney's birth in Mexico. Look it up. The law was changed in 1940 but the ones in place in 1907 has a child born to an American citizen father taking the citizenship of his father. This means that George Romney was an American citizen at birth, not a natural born citizen , but a plain-jane "native" citizen.
I'm not a Romney fan and would love to have had him ineligible but his father was an American citizen. I'll try to find the link but the info is there about Mexican citizenship laws and how they were applied to foreigners living in Mexico who had children.