In what order are OnEnables called on a complex object?

Question

Unity

Hello. I have nested GameObjects on the stage that have scripts attached to them. Every script has an OnEnable. Previously, I always thought that the root OnEnable is called first, then it goes to the child ones, and so on, that is, from top to bottom. But today I noticed the reverse order of the call, starting from the bottom up, that is, from the most nested to the parent. It seemed strange to me, I decided to double-check it, made clones of identical objects, started turning them on one by one and it turned out that the call order was really random. Either from root to child, or from child to root. Explain why this is happening. Thanks in advance.