RobertK:
We don’t actually. And I think if we find ourselves wondering about this these are moments that should be understood.
I remember when I was young wanting to confirm that I was one of those who had triple hetu. What conditioned this? in my case I wanted to feel I could quickly understand Dhamma and get the results of satipatthana, so it revolved around desire and clinging to my important ‘self’.
This sort of desire can actually push one to try to prove they have the hetus - so we might try to get jhana or lokuttara - but this sort of desire is not the path. If this clinging is strong one can persuade oneself (and even others) that they have jhana and more. (On the other hand desire can be understood, and even be an object for satipatthana).
If we are double rooted then that is the way things are. We can redouble efforts to understand the nature of the present moment. The right causes bring the right results sometime in the future.
I think this is where having faith is really important. We have to have faith in ourselves and try our best. Even Bodhisattas, future Paccekabuddhas, and future chief disciples have to put in 100% of their effort to become enlightened.
It’s hard to attain jhana and enlightenment in the household life even for one with great parami.
Even the wheel-turning monarch needed to practice Brahmacariya as a layman to attain jhana.