Purple branches

This is very common. Usually turns out to be sunburn, which is completely fine. You can diagnose this by checking the sides of the stems pointed away from the light, if they're still green on the underside, its sunburn. Nothing to worry about. If the entire stem is red or purple, it could very well need more phosphorus. This is also a common problem. Less common are genetics, which you should already know if that's the case, and temperature. If the temperature drops to the low 60s at night, this can cause purpling. I think that covers every base! Good luck!!!