Excuse me? Are you saying the child of someone who has crossed our border illegally as in the manner of invasion should automatically be a US citizen. To me that is the most absurd notion that I can think of. The founding fathers were thinking of this issue when the issue was addressed. They always rewarded those breaking our laws in the Constitution didn't you know that?
First, the plain language says anyone born in the US is a citizen. Second, the 5th and 14th Amendments prohibit government to deny any "person" (not "citizen") equal protection of the laws.