Purple: Growth and genetics vs. frostbite

So i see how some of my friends like to let the cold get to their plants sometime for purple aesthetics, but this is obviously detrimental to the overall health and quality of the plant/flower. What from the cold causes the purple, is it the moisture in the plant freezing? And what is the purple a sign of in genetics? I know it doesnt just mean dank, iv'e also heard its sometimes caused by a plethora of nitrogen... idk.

I'd love to hear what some of the marijuana experts of this site have to say about this, go at it!
Sincerely,
A stoner/grower.

Genetics causes purple not weather.

phosphorus lockout causes purple, and is caused by low temps, under 50/60 degrees. its not a deep purple, but ya it gets purple. i dont do it tho. my babies get 72degrees of cool from day 1 to harvest

im not sure but i got some purple diesel from http://www.medicinalorganic.com and i hope its fire. Its says it turns purple after 2nd week of flower no temp change nec. so we'll see !