Board Thread:General Discussion/@comment-77.22.203.164-20131030101744/@comment-5230978-20131030125507

Accel's surname is stated to have three kanji and "Kihara" has only two, so he is not a Kihara. And it's unlikely that the scientists and the Kiharas would refer to Accel as Amata's son, unless it was a scornful label; they would rather call him Amata's experiment/pet/toy or something like that.