im somewhat down the middle of things...
i grew up on stuff like zeppelin, the beatles, yes, rush, king crimson, simon and garfunkel, boston, the moody blues and even judas priest, black sabbath, metallica and the scorpions, etc.
then when i was around 13 i explored metal a bit more, getting into solo ozzy, megadeth, slayer, testament.
then at 15-16 i explored more underground metal, like emperor, opeth, carcass, in flames, etc etc. At this point i also found out there was a whole new world of underground classic/progressive/psych rock that i hadnt heard before, attached to such bands as king crimson, yes, the beatles, etc which i was already into...
and since then ive been a big fan of both genres...and i continue to dig and dig the rock genre to find new bands, and occasionally new metal bands (however ive found very few new ones or ones i havent heard are worth my time)...so anyway, i got into Opeth around the time i was 16 i beleive...i had to get used to growls in general at the time, not just for opeth exclusively.