Why speak in hypothetical?
Britain doesn't work that way and never has. Shoot, no other nation does either. Name one nation that states if you are born to its citizens off its soil that you aren't a citizen of it. Its insanity to say that. Of course a child inherits the citizenship of its parents.
Just think for a moment, what would happen if what you suggest were the case and you were born on say, a cruise ship crossing the Atlantic. Because you were born in the middle of the Atlantic you aren't a citizen of your parents nation? That would literally have created thousands and thousands of stateless people. That is a situation all nations want to avoid, stateless people are a real headache for a lot of reasons.
Now with regard to how citizenship passes from mother to child, this is something that has changed a lot over time. There was a period in American history for example, where, a British (or german, or french what ever) Woman marrying an American man would take up the citizenship of her Husband. So in marrying an American Man, she relinquished her own native citizenship and became an American. That was actually the case at the time Chester Arthur was born. Doing things that way did simplify things quite a bit. It took some uncertainty off the table with regard to the citizenship of the children produced from such a marriage.
This was not the law at the time Obama was born. However, it was still the case, the father's citizenship carried more weight than the mothers. Sexist yes, but there it is, and there it was.
Regardless of all that, Obama was still quite likely born in Hawaii to an American Mother, with a British Father. he was born American, and he was equally born British, which is why Obama admits in his books and on Fightthesmears that he was born under the British Nationality Act of 1948.
Natural Born Citizenship is a description of birth and states that the child was born under only one jurisdiction, or the child was not. Obama was NOT born a Natural Born Citizen - born under the sole jurisdiction of only the United States.
The Founders decided they wanted to exclude everyone who was born under more than one jurisdiction, so they deliberately included the requirement that the person have sole allegiance to the Untied States from birth, the mechanism used to denote this status is Natural Born Citizen.
Obama fails this test.
Sez who? Orly Taitz? Female British citizens did not have the same rights, as males, to pass along British citizenship, to their child born abroad, until the 1970s.
Go on try again.