Responses
The two Ilegenes manga series are prequels to the Ilegenes novel, "Ilegenes: The Genetic Sodom". The mangaka had to add the girls in the story in order to make it an accurate portrayal of the events that led up to what's happening in the novel. If you're interested in the novel, you can read a summary of it at issyapir's livejournal.
I wonder why the mangaka tone down the BL element with adding girls in. Maybe to broader the audience ;)
Personally I love it if it were a real shounen ai or even YAOI :p
But it's interesting nevertheless :)) <3<3