I grew up moving somewhere new almost every year, so I have no childhood friends.
I find that most people don't either because friends change over time as is the nature of human dynamics.

even my own brother who I have not been separated away from since his birth, for more than a few months at a time, is not as close to me as 70% of my friends.

through my experience, it's the friends that closely resemble me that stay with me the longest.
Those that share my same view points, beliefs, experiences, etc. are the ones that I share the strongest mutual bonds with because to me their success, is the success of at least one of our rare kind.

we're all humans, we're all prone to disagreements and arguments, and each one of those opposing solutions to our issues threatens to sever the ties of our relationships.

by bonding with like minds, I feel like i am caring for an extended family member. someone who can express genuine empathy as they would more than likely be living a similar life to mine.

without that sense of comradeship, and being united with a common view, you can't really have long lasting, meaningful relationships.

I have only made such bonds with friends from the military academy and i'd hold a target on the range, 500 meters out for them any day, because I know they'd do the same for me if I felt the need to be that much of an @$$hole lol. and because we're all almost exact clones in many ways.