This question is easily answered by the fourteenth amendment that states "two kinds of citizenship; by birth and by law (or naturalization)." So, if you were born within the United States' borders, then you are a legal citizen, whether or not your parents were born here or a citizen of the law. But the other way you are a citizen by birth is if your parents are both citizens of the U.S.A and they give birth overseas, then you are a citizen. Birth by soil can also be on military bases and in American territories, whereas birth by, for lack of a better way to say it, parents, they can have you anywhere and you will be a citizen by birth. I hope this helped! If not, check out the 14th and 12th Amendments, they might give you more insight! :)