But, joking aside, I think the mom just got incredibly lucky that she had twins in this case or else one of the two might have been in for a slow decay unless some mcguffin to cure the rot appeared. Their Mana is probably a close enough "match" to not trigger the negative effects.
Really happy with the progression, good to see the brother being the one skilled with magic rather than the reincarnated MC, not only being smart, but overpowered with magic too would be lazy writing and seen too many times
So chapter 3 is gonna be, defeat a den of bandits and human traffickers as a child. About on-pace with a typical isekai, maybe a bit ahead, this kinda subplot usually happens at around chapters 5-8
I really like ghis mamga because the MC had a twin brother, that's unique. Two the brothers are really bonding and close with eachother. And 3 i feel like they're using the fact they're twins with the mana resonance and that's really cool. Hope this manga keeps the effort up