That is a total lie, the 14th amendment is absolutely clear and it was passed after the Civil War with the explicit point of granting citizenship to black slaves who, you'll notice, did not have citizen parents:
> Section 1. All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.
If illegal aliens are not "subject to the jurisdiction thereof," it's not possible to arrest them for a crime--that's what the phrase means.
The language excludes diplomats, foreign soldiers on US soil while they're fighting a war with the US, and (given the context of when the amendment was passed) Native Americans who hadn't yet been told that they were subjects of the US.
Yes, under current law, almost every baby born in the United States or its territories automatically becomes a US citizen at birth, regardless of the parents’ immigration status, except for certain children of foreign diplomats or enemy forces in hostile occupation.
Even if you're here without permission, you can be tried in our courts, and are subject to our jurisdiction. I'm willing to be swayed, but it has to be compelling. Diplomatic immunity or maybe recognized tribal member on recognized reservation when they were being disenfranchised are the only times I'm aware of where people are physically within the States and DC and not subject to the jurrisdiction thereof. Perhaps if a child is born in an internation vessel at port, or in a duty free shop or a customs free trade zone. Territories and such get squishy, it's usually not clearly stated when the term United States is meant to include those portions of the country that are not a State; but the 14th ammendment is understood not to apply to territories. Citizenship at birth is granted in some territories (at least Puerto Rico) by federal legislation.
That said, upthread you claimed:
> this is only true if your parents were citizens
And now you claim something about illegal aliens. There's a whole range of circumstances, some of which would have been uncontemplatable at the time of the 14th ammendment. If you are born in the US. You claim citizenship only if parentS are citizens. But if only one parent is a citizen, or both parents are permanent residents, or the parents are authorized visitors. For the historically impossible situation, what if the child is carried by a surrogate with authorized presence and the parents are non-citizens not present at birth ... that child is a US citizen by birth, and not included in your statement above.
> Section 1. All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.