Been looking for a thread like this, and I agree with this, its a real turn off when the videos indicate that if the Step thing wasn't there we would not have done it.
I'd like to tell you some of my findings from mainstream media, please check them out:
Grand Jete (Mother and Son, scenes include fellatio and she even gets pregnant)
The Quietude or La Quietud (Sisters are attracted to each other, mutual masturbation and at the end of the film maybe confess feelings to each other).
Edit: In Grand Jete its a handjob scene not a blowjob, my bad.