It sounds like your mom is a little unhinged to be honest. What you’re describing is verbal and emotional abuse. As for her opinions I understand the tradition of where they came from but the level of seriousness to which she takes it is alarming, to say the least. She berates your siblings and pits them against you in regards to attractiveness based on something they ultimately can’t control, comments regularly on dark skinned people being ugly because they’re darker skinned, and has openly admitted she reproduced with a white person so her children would be lighter skinned and therefore more attractive. That’s mental man. Get your mom some help.