the ratio of CBD to THC changes over time in individual plants, becoming greater to CBD as more trichomes turn amber during the maturation process. It is highly dependent upon the timing of harvest, and not so much the genetics.
When the trichomes are clear, they are heavy to THC and produce an energetic, cerebral high... when the flowers are allowed to mature further, the trichomes turn cloudy, then amber, and in each phase the level of CBD increases in relation to the amount of THC, and flowers high in CBD produce the "couch-lock" phenomenon, which is better for pain remediation and sleep inducement.
(trichomes are the resin production "glands" on the flowers and adjacent tiny leaves which, under the microscope, look like little mushrooms of resin and are used by medicinal growers to determine the ratio of THC to CBD)