Probable chronological order of the sex scenes:
1. Son rapes Aunt - unnecessary, illogical scenario which everyone hates; there's no reason for it to happen but it did happen.
2. Aunt fucks Dad - this sly, manipulative succubus is taking advantage of the Dad's boring blue-ball storyline.
3. Son fucks Karen - this perverted jackass needs to get laid as soon as possible before he goes to college.
4. Daughter losses virginity to Ben - far likely scenario post-prom dance.
5. Karen fucks Dad - daddy issues, it's likely that Karen is his Daughter. Dad did date Aunt way back.
6. Son fucks Mom - what the majority has been waiting for; the only reason why I continue to play this god-awful adult game.
7. Dad fucks Daughter - Congratulations! You're officially a nympho, now contemplate on having a threesome with Karen.
8. Son fucks Sister - unlikely but son's psychopathic, impulsive tendencies may lead him to rape his own sister/
9. Mom and Dad have sex - one last sex to the parting divorcees.
I'm calling it now, Karen is Dad's bastard daughter. Full incest circle, dad is basically going to have coitus with two of his daughters and son is going to pound both his mother, his sister and half-sister. Let us pray to the hentai gods that Aunt and Mom would go at it! Unless Kyle wants to screw us over and have Dad and Son suck each other.