I don't think that there are many brothers who actually hate each other, although it may feel like that at times.
Arguing with your siblings when you are growing up, and even later on as adults, is perfectly normal, and a rite of passage for most people.
Boys in particular may argue as increases in testosterone cause them to anger more easily, and again, this is perfectly normal!
When you are a child you do not have the complex reasoning capabilities that you have as an adult.
These develop as you mature, and part of that process is probably through bickering with your siblings. Through these arguments you gain insight into how people react when they are angry, what "pushes someones buttons" and how to resolve a disagreement.
The saying "there is a fine line between love and hate" is particularly relevant in these kind of scenarios as underneath all of the bickering, families love one another, and though emotions may flare up from time to time, this connection does not tend to go away.
