I am on level 33 and some of the lower perks are still grayed out, so does it depend on a combination of the main perks and level ?
I am sure on the previous games you had to add all the main perks before you could get all of the lower ones.
If you highlight the perk at the bottom it will show a requirement of level and SPECIAL/Perk level for example L15 + Luck 6 or at least that's how I understand it. You may need to upgrade a lower level perk to full before it unlocks.
But as I said I still don't really understand it, only figured out how to do explosives the other night
That's exactly what I thought, you can only get some of them once you have maxed out the main perks, I have finished the main quest, and managed to keep all the factions happy, although I still have to decide if I want to help the institute further,
and at that point I guess I will have to fall out (pun intended) with the Railroad, the Minutemen, or the Brotherhood of Steel, I have been wearing power Armour for quit a lot of the game, but it makes you a bit bold when dealing with anything but Death claws and the big rad scorpions, oh and the queen Mirelucks.