Two points:
1) Personality and behavior are strongly influenced by both the physical makeup of a child as well as the nurture (or socialization) of the child. A child that is physically wired with more physical sensitivity is going to be fairly different from the child without that awareness and sensitivity. So a pair of siblings can be very different.
2) Can we eliminate hierarchical groupings? So far, to the best of my knowledge, only a few social experiments have been successful over an extended period of time. None of the so-called communist governments has been successful in eliminating that hierarchy. Every single time someone has snatched the reins of communal control and grabbed the power for themselves. Mao, Stalin, Castro (etc); they and many others have used the peoples revolts to seize control.
We humans have a very difficult time working together without a leader or an ideal to work with. And yet, humans seem so hardwired to work in groups. But personalities collide. Without a strong & fair leader, groups tend to de-volve.