My brother and I are 18 months apart. We fought a lot until about middle school. After that we became very close friends, I would be very sad to not have him in my life. My kids fight a lot too, but I can tell that underneath they like each other, but they are also competitive with each other (my DD7 instigating it a lot of the time as she is less mature).

By the way, I was the first born, so whenever I think about my mom's saying about the truck I realize that I was the truck.. as a baby my brother was actually very sweet and calm and apparently had the exact opposite temperament to mine which was a welcome break for my mom. However I believe that he is more gifted than I am.