Joseph- we can take aunts and nieces out of the topic. My children are nothing like my brother in laws.
I think what you mean is that in an ideal family, you want to marry someone that is like your mother/ sister (or the wife’s father/ brothers) because you want to emulate the family values. Other times, you look at the flaws in your family and do everything you can to marry someone that is different, to spare your children the issues that you grew up with.
When we first married, we discussed what we didn’t care for in our parents relationships, or what we didn’t like about how we were raised, and agreed to change some things in our children. Our parents had both made some pretty big mistakes. And you know what? So have we. Some days, I strive for perfection in them. Some days, I say “if you can be a better man than your father, I will be happy.” There’s a certain pride in knowing your son has achieved more than you.
And sometimes, you need to find someone with different hashkafos to give you a new perspective.