Hate to be that guy, but this a pet peeve of mine that pisses me of...

The term "birthright" means "a right that is derived from the circumstances of your birth". Virtually ALL countries grant citizenship by consequence of the circumstances of birth, but what circumstances they consider vary. For some countries, the circumstance is "birth happened in the soil of the country" (jus soli), for others, it's "birth was to parents who are citizens of our country".

I said "virtually", because there is one SINGLE exception. The Vatican. Ok, there's the SMOM, but do they even count?