Francis, after reviewing your posts we have decided you are a Russian operative with intent to divide us.
LOL and just kidding. I enjoy your post and responses. Keep them coming, theoretical or not. For your friend in 1999, further proves what organ is really in charge of the human body.
WebMD or your son's pediatrician would be a lot better than a chat board for advice. There is good information on Creatine risks, unknowns, etc. It's not a drug, so not regulated by FDA, meaning impurities, labeling, etc could be more suspect than a drug. I'm sure you have read up on it.
But yeah, my son took some this fall when lifting a lot. He is two years older than your son. I added 5g to his morning shake. It was everyday and strictly for eight weeks. I think whether your son takes it is your call and based on his maturity and the level of communication you two have. For my son, I trusted him to drink plenty of water and to tell me if something was different (how he felt, the color of his pee, if his stool was different, constipation, lightheadedness, etc, etc.).
Since he has no identical twin, I have no idea if it had any effect or not.