Both. My bf is decently high, & I have a fair amount of lumps/pebbles in my chest. I'm very gyno-prone, & my bloodwork proves that my estro & prolactin both run on the high side naturally. I think some of it is pubertal tho - I've always had dishearteningly-shaped tits, even since I was young. Prolactin wants to jump in response to anything, & also estrogen picks up easy enough too. First cycle ever was gonna be 80mg of ProDienelone & 20mg of Epi/day. I woke up on the SECOND day with inflamed, puffy nips. Dropped the Prodienelone after day 5 & went full Epi instead. I've since learned the hard way how my body responds & what I need to take if I want to run Prodienelone the right way. You learn quick when the alternative is wearing a sports-bra
Now I'm explaining to 230lb f*ckers at the gym how to control their gyno on their gram of test lol. People never want to take the time to learn how their own bodies actually work.
Gyno is part of the game - it comes & goes, you just have to understand how to be the one dictating that.