i have a biak that still has not changed its color.
i havent had it long but it will bite pretty much at will i use neoprene gloves to handle it and sometimes it bites more than other times.
ive heard that most under a yearling will bite but i havent handled any adults.
im sure mine was an farmed or wc baby im leaning to farmed.

also note that some locales are supposedly worse than others and ive been told that biaks are either really nice or they are meaner than a hornet as adults im still trying to handle mine as much as possible.