The way I see it is this; If anyone recalls the conversation between Chi and Demo during their time in the Land of Tainted Souls while in search for Mimi's whereabouts (This of course can be traced back to the page called, "Chi's a weeaboo" at Snafucomics.com). Chi was in the middle of telling Jeff off when she was abruptly cut off by her fascination with a picture of Mimi in her true with her mother (Blossom) and brought up that the name Blossom sounded familiar after which Jeff responded to her by saying her name was Blossom, to which Demo stated that she was a well respected warrior in the eyes of Aku. Just because Chi resembles blossom doesn't necessarily mean they're of any relation. Aku is able to take the form of a male and a female, and he is able to manifest new beings, my opinion is that because of his intriguing curiosity for Blossom and his respect towards her, he could have quite possibly created Chi in Blossom's image (If you think the style of her hair really matters to how she looks). Either way, that's my opinion on this matter.