In fact, Kanna is the older sis in this family (lack of good nutrition or something stunted her growth? lol.) If you read the subtitles on the DVD, Naraku says, and I quote, "Go now. Once more. Already your older sister, Kanna, has been dispatched." Even though Kanna looks like she's like 8 or 9, she was created before Kagura. Wow.
Submitted by Kitana