Responses
Wait didn’t the ladies at the beginning say that the father was unfaithful....
http://www.mangago.zone/read-manga/ore_sono_kao_kirai_desu/uu/ibx_chapter-1/pg-3/
Also realized that they’re 3 years apart in age, so definitely not twins :)
I’m praying that they aren’t secret twins (⊙…⊙ )