umare mo sodachi mo chikyuu desu yo 生まれも育ちも地球ですよ [My place of] birth and rising is Earth.
In west Philadelphia Earth, born and raised.
...mo ...mo 〇〇も〇〇も X and Y, too. X and even Y. This is the mo も parallel marker.
Koro-sensei is offended because he was called an "alien" even thought he was born and raised on Earth: a genuine Earthling. Totally not an alien. Nope. (or so he claims.)