I've been mulling this over in my mind for a while, about how siblings have such different personalities often. And then I read this article. http://www.brainchildmag.com/essays/winter2012_ozment.asp
I have one sister, two years younger then me. Saying that we hated each together growing up is putting it politely. We had very physical fights until i moved out at age 15. We never did grow closer. She has lived me with over the years when she has gotten into a jam, we talk once in a while, hang out every couple months, more because we feel like we have to because we are siblings not because we enjoy each other's company. I love her because she is my sister but I don't like her, never have, probably never will.
I've got 4 children, 2 girls almost 4 years apart and 2 boys 2 years apart. My girls remind me so much of my sister and I. My second daughter is a carbon copy of my sister, isn't that ironic. I feel for DD1 often because I remember just how sneaky my own sister was, and there she is, living in my house, even smiling that same little grin my sister did. They fight so much that we normally do not all hang out together as a family. We rarely get whole family days but when we do, it is very common to spilt the girls up, DH and I each take one with 1 boy and go off and do different things. Or I invite a friend for one girl to come along which shifts that girl's focus from "what can I do to pester my sister all day" to actually leaving her alone. I'm torn between thinking that if they have enough time apart to develop their different personalities and interests then maybe when they are together, they will enjoy each other more or thinking that that it doesn't really matter what we do. Who knows!
Of course since every kid is different, they all get treated differently. It just isn't possible to treat them all the same. I do find myself being harder on DD2 because she so consciously acts up. DD1 is very much a rule follower and I don't have to worry about that but she has her own demons that will follow her throughout life which is other problem that plays into the sibling relationships. She would of been an excellent only child.
Do you find that your kids seek out different roles within the family? I've read the rivalry books, I'm not looking for direct answers, more of a broad discussion on sibling relationships. So what are your kids like?