Candidates for who gave Bam 'the talk'
Jinsung: very likely. adult who has spent a lot of time around bam and is very mentoral/fatherly toward him. however, I can see jinsung learning that bam doesn't know what sex is and just... deciding to not tell him. better if he doesn't know
Rachel: makes sense in that she taught bam everything, but they were both young when she was coming down to the cave and I feel like even if she knew, she wouldn't tell bam any details. gives me 'a stork does it' vibes
Khun: possible in season 1. he sees that little boy being clueless and is like "i have to Educate him so no one Takes Advantage of him". I feel like after season 1 he would just assume that bam was told by someone else
Shibisu: again, probably only in season 1. he canonically considers himself a 'father' (in a half-joking way, I know) to a couple characters. I think he would give bam the talk in more causal way, more like he's teaching him how to pickup girls than a having a Very Serious Talk
Hwaryun: I don't see this one. it's not her job and she knows that he isn't interested in anyone. why bother
Hansung: another adult who spent a lot of time with bam but he probably dgaf
Evankhell: honestly the one I think is most likely. jinsung was a coward but evankhell will explain sex to bam in very blunt and thorough way. also "if you get anyone pregnant I will kill you" vibes (in a loving way)
Bonus:
V is the one who has to do it. you're his father so get to fathering
