I'm a ( 35f ) and my sister is a ( 40f ). I currently have no children and she has an almost 13yo daughter.

TLDR: I feel like my sister isn't the best mom/wouldn't provide the best home environment so I'd rather my childless brother take care of any future children I might have if I were to suddenly pass.

I've always wanted to be a mom, but don't have much of a romantic history, as most of my relationships started online/long distance when I was young and I'm generally an introvert even as an adult, so don't make many connections. I'm divorced from my husband and ( in hindsight very thankfully ) never had kids with him when we were married ( early to mid 20's. ) I tried with my most recent ex-boyfriend for about 3 years, but during that time discovered I have PCOS and very irregular cycles so pregnancy never happened and will likely need medical intervention.

Recently my sis asked who I would have take care of my child if/when I have a child in the future and something happened to me. I honestly answered that I would choose our brother. ( My twin. )

For context, my brother is an introvert and I don't know if he's ever even been intimate with someone, but has never had a partner as far as I'm aware. ( Edit: He's also the nicest, most caring and giving person I know. ) My sister has only been in 2 major relationships..a very abusive one in her teens through her 20's and her current marriage that's full of mistrust and cheating ( on BIL's end ( 57M )..but because of her past she hasn't escaped the cycle of abuses and sticks around. He is very toxic and we all just tolerate him because sis won't/"can't" leave.

She raises my niece in a very ipad kid kind of way. Too much leniency, ipad at 2, cell phone at 10 and not a lot of supervision. I would NEVER raise my kid the way she has. I don't agree with her parenting style and would NOT want my BIL as a major male figure in a future child's life, regardless of gender of the child. I wouldn't want them taking after BIL's habits and disrespectful nature or my sister's passiveness in not standing up for herself and allowing the disrespect. ( Or not taking steps to heal any past trauma the way my sister won't. )

I told my sis basically that I would want bro to take care of my kid because my preferred parenting style differs from hers and I don't believe she's be able to follow any guidelines I'd leave in death ( especially if BIL was still around ) and she was PISSED!!

My bro, while more than accepting of being my possible future child's caretaker thinks I was too harsh, my bestie is on my side coming from a family that was also pretty dysfunctional. I wanna know if I was TAH for dismissing my sister as a caretaker since she's the only close person I know who has actually/is actually raising a child. Just because I don't like my BIL as far as I can throw him and think she wouldn't parent my child "right."?