what makes it purple?

I've heard that what makes cannabis purple is simply the temperature of the room it was flowered in and i've also heard that was BS and that weed was purple because its in it genetics... but then why do i get people with cannabis they call purple thats not even purple?

because they don't know what they're talking about.

Purple plants is all in genetics, atleast true purple plants are... some people with hold nitrogen to cause their plants to turn purple or they chill the grow room to cold... but both of those will cause a bad smoke

Indeed, color is about genetics. If you manage to get a color without the genetics you disfigured your plant. Blueberry turns bluish, Purple Kush/purple widow/lavender etc turns purple, white widows turn white, bubbelicious actually goes pink. Beware of people yammering on to infinity that don't know what they're talking about in the slightest. I'd watch for people who start saying "dude" and "man" a whole lot while they're telling a story about how they grew purple/blue bud from a plant they stole from the mayors house and grew in front of their car's headlights in the garage.