To me that looks to be genetics, though how heavy the spotting is my depend on environment as it develops. I don't think they are caused purely by environment from the look of them as they don't seem to be a 'problem' more just a colouration in the plant.
One of my phals looks different every time it blooms. Random purple blotches in no discernible pattern and in different amounts... I wouldn't be too worried. The amount of coloration can change depending on light spectrum and intensity as well as the type of other nutrients it receives.