I knew it I was right it's really obvious they're brothers

they already revealed/confirmed it in chapter 68 (the end)
https://www.mangago.zone/read-manga/minmotion_syndrome/uu/br_chapter-206832/pg-25/

Like you, I had a feeling they were brothers right when we met the evil guy's dad at the restaurant back in chapter 6: https://www.mangago.zone/read-manga/minmotion_syndrome/uu/to_chapter-6/pg-10/
I had a feeling that was the powerful Alpha, that they mentioned ML's omega dad was involved with, was the father