What causes the friction between the two brothers in Bloodchild? Can their story be considered a reconsideration of the Biblical story of Cain and Abel?

The conflict between Qui and Gan centers around each brother’s different views of the relationship between Terrans and the Tlic.
Raised from birth to be the host for T’Ganoi, Gan has always felt loved and honored by the Tlic. He believes being a host is a good thing, not only because he accepts it as a necessity but also because of his affection for T’Ganoi.
Qui, Gan’s older brother, has not been afforded the same luxury. Qui regards the Tlic with suspicion, remarking to Gan that Terrans are nothing but breeding animals on the planet. Qui taunts Gan about the bloody, violent extraction of Lomas’ grubs while pointing out that T’Ganoi is just using him. Qui is cynical and jaded because he has seen a host die during the birthing process, and he has never had a personal relationship with a Tlic like Gan has.
When the brothers fight, it’s because Gan considers Qui’s point of view as partially true, and he is distraught about his complicity in a system by which he is exploited.
The only parallel I see with the Biblical Cain and Abel is that Gan, like Abel, accepts his destiny and aims to please those around him. On the other hand, Qui challenges the status quo. I don’t think Qui’s attitude is steeped in jealousy like Cain, and there’s no indication that Qui plans to kill Gan.