Classifications in a continuum always seem fake when you get near the borderlines. Basically there are pure BLs of varying aoa's (ages of attraction), hetero-BLs or 'smoothophiles' who like women and boys, but not men, and gay bl 'chicken hawks' or classic pederasts whose a.o.a. for males crosses over into the 18+ zone but stops at the first beard growth, and more broadly attracted gay BLs who are attracted to boys but whose a.o.a. may allow a life-long partner. Then there are bisexual bls parallel to the various gay bls.

I've known two young men who were mainly attracted to boys but could also get quite interested in gay sex with men at times, and could also have sex with women, ESPECIALLY if there was a chance they could get the woman pregnant. The idea of possibly producing a boy seemed to charge them up red hot.

Then you have to consider the fact that almost all heterosexual men will not only find boys and younger men attractive when they're sex-deprived in prison (and would be absolutely inflamed by younger boys if they were there) but also, where their local society tolerates it, will often go to having sexual services rendered by young looking guys who will provide them oral or anal sex. The number one fantasy of hetero men on female phone chat lines is the primal urge to have sex with women from behind (vaginal mostly but also anal) and studies have shown that if straight men are just shown photos of naked butts, the young male butt looks perfect to them. (These are old data I heard about in the 80's - I can't give you a citation). Therefore, straight men by nature are 70% primed up to have sex with boys and it doesn't take much to push them over the edge... a couple of weeks in prison, a change in cultural values, a chance to be sneaky... they get right in there and mess up the classification system.

St. Paul's observations on these hetero males have caused endless trouble for actual gay males, so this classification thing is important in the Christian context. The technical term for these boundary-breaking straight males is 'rough trade' or, in the bible, arsenokoitai ('sodomites' per King James, 'male-fuckers' in the Greek). They are distinguished from gay men, pederasts and anthropaedophiles in that they don't have their major emotional relationships with males, but instead with females. Young males are a sexual vessel to them and they hold themselves at emotional arm's length.