A couple of thoughts come to mind:
1. I'm the BS, but I don't think I would run to the hospital for my MIL's sister's husband, especially if I had only met him once. I wouldn't think it was weird if my WS wanted to go, but I would doubt that he would based on how he is with his own family.
2. Coincidentally, my parents are very helpful. WS finds it annoying sometimes that we spend so much time together (and I understand, because they can drive me nuts, too) but also (and this is the part that bothers me) has no problem asking my mother for free babysitting whenever he has something he needs to do and I'm still at work (we work different hours). My feeling is that you don't get to complain about my mom wanting us to put dirty dishes in her dishwasher and not her sink, and then turn around and ask her if she can come over on Tuesday night to watch the kids for an hour... And my parents are like, the ideal in-laws in that they pretty much respect all of our rules w/ the kids, so there's no drama over them buying too many toys or feeding them stuff they shouldn't etc. etc.
3. I read an article (I think on Slate?) recently that said children were asked to rank which grandparents they were closest to, and overwhelmingly it was maternal grandmother first, maternal grandfather next, then paternal grandmother and paternal grandfather was barely ranked, but it was funny because most people in heterosexual relationships tend to live closer to the man's family (I can't remember if this was due to work?). There's also a saying, "A daughter's your daughter the rest of your life, a son's a son until he gets a wife." I sent the article to my mom and we talked about it, and she mentioned several of her friends that have sons/daughter-in-laws/grandchildren, and have expressly told her that they need to tread carefully with their DIL, because if they argue or disagree about something, their DILs will remove access/visitation/time with their grandchildren. And, I know I'm not getting the full picture of the relationship, but these are women I've known my whole life that are lovely, genuinely non-toxic people, so it does seem like a pretty harsh reaction from their DILs.
While there were only seven people on the call, we had a 100% consensus that WS thought this concept of everyone going to the hospital weird and BS thought it was normal.
I think statistically speaking, men cheat more frequently than women, so were most of the WS you asked men? And most of the BS women? I wonder if this has something to wo with it.
Lastly, in my personal experience, my relationship with my parents is that, if I woke up really sick tomorrow morning, I could call my mom at 6am, my dad would drive her over, she would come to my house, get my kids ready for school and take them, even if it made her a little late for work. No questions asked, one of them would leave work early that day to then pick kids up, and they'd drop me off saltines, gatorade, etc.
My in-laws live a plane ride away, so they couldn't do that for us, but they live 15 minutes away from my nieces and nephews. LONG story short, my sister-in-law passed away a fee years ago and my ex-brother-in-law is a piece of shit. The kids have a home, clothes, food, but otherwise XBIL generally ignores them and expects the oldest to take care of everything while he's busy getting his d*** wet. The youngest has frequently been missing the school bus, frequent absences, etc. My in-laws are both retired and could easily pick youngest grandkid up in the mornings and make sure he gets to school, and then go back home to bed or whatever they do all day as they stay at home. Instead, they join in on lecturing oldest grandkid that she needs to do a better job with the youngest. Sorry, but it shouldn't be a grieving teenagers job to basically be a step in mom for her elementary aged sibling. It sucks all around but if XBIL is a shit parent, and SIL is deceased, it would be nice if grandparent in-laws went above and beyond for poor kiddos, but... they don't.
I went off on a tangent here, but maybe you're on to something with some people having good, reliable, loyal, empathetic families and being more likely to be a BS, and some people having selfish, self-centered, unavailable families being more likely to be a WS.
[This message edited by ibonnie at 3:23 AM, Monday, May 22nd]