No Ai is not Taiki's mother SPOILERS BELOW: Hikaru was molested by some other girl named Airi and somehow Airi got pregnant and they had a kid named Taiki so basically Ai has no relationship whatsoever with Taiki he's not Ai's biological son while Aqua and Ruby are Taiki's half siblings becuz Hikaru is the same father for all of them... Hope that helped I suck at explaining things