Try get him to sit down with you and watch some videos like the WEED series by Dr. Sanjay Gupta.
https://www.youtube.com/playlist?list=PLym_dC-PXmBnWqfw2XZIdm8ZuuW-zo2ie
When you do, have a joint of some nice, smooth, low flavour, high cbd, low thc bud hiding in your pocket.. because if you...