Mistaken about what? My brother in law is English, as in born in London. My sister is of course a natural born citizen. They have two children, both of whom were born in Chicago. Are those children eligible to run for POTUS? If they are, your point is wrong.
At the time of Obama’s birth, his mother would have had to have been an American citizen with at least 5 years of citizenship after the age of 16 (or is it 14?). She was only 18 when she gave birth and was therefor unable to confer citizenship on him as the sole citizen parent.
The children do not qualify as natural born citizens according to what the Senate (including the affirmative action figure bastard-in-chief) signed reagrding McCain’s status. As to a final answer, only a supreme court functioning in a the now defunct Constitutional Republic could have determined that.