User blog comment:Master Sima Yi/Assassinews 12-05-'15 — Assassin's Creed: Syndicate has been revealed!/@comment-4786308-20150714221702/@comment-13471981-20150714222045

Yup, not sure where the confusion came from. French Ubisoft Community Managers called Henry the adoptive son, but I'm not sure if that means Ubisoft was mistaken during their original announcement at the Montreal con or if fans misheard/jumped to conclusions.