Here you go buddy:
(Imagine this as epic scrolling text, in the style of a Star Wars introduction)
Ophelia, Aliza and Andrew are siblings. Hunter is their father.
Hunter waits for Ophelia to turn 18 so he can corrupt her, because he's definitely going to care about age of consent kek.
He's not bothered about corrupting Aliza, his other daughter, as she's fat (at the time).
Before he can corrupt Ophelia, she meets David, marries him and gets pregnant with Brenna. Curses.
Then David knocks Ophelia up again, with Sterling. Double curses.
Then David knocks Ophelia up with Catherine. Hunter is quite annoyed now.
Because of Ophelia and Aliza moving out and some reason that I forget, David's sister Keira and David's mother Nora move into Hunters family home. Something about needing to sell their own house? Cost of living? Whatever, not important.
One day Hunter discovers young Andrew jerking off with Keira's underwear and takes the opportunity to say "Hey, you're a pervert, why not learn from me how to corrupt women with drugs and stuff."
Andrew goes along with this, discovers Hunter is not full of shit and, incredibly, can actually do this to women. They work together to corrupt Nora and Keira into becoming nympho exhibitionistic incestuous sluts. Good times.
David discovers this development, walking in on his sister and mother mid-coitus. Bad times.
David beats the shit out of Hunter and threatens him, Hunter promises to leave everyone alone and runs away to corrupt women around the world vowing to return one day. Well done David.
Nora and Keira come to their senses (for now?) and move to Canada, where Keira (pregnant with... probably... Andrew's child) gives birth to Lucia.
Andrew transitions to Drew and carries on applying the techniques Hunter taught him.
Other than David, nobody has any idea what just happened. David is haunted by the idea that his son will one day inherit the magical "Sex God" powers Hunter's bloodline carries (via Ophelia) and treats Sterling poorly as a result.
Fast forward 19 years - Sterling returns home after the death of David and the plot kicks off, with Hunter returning to finish what he originally started - to impregnate Ophelia (which has been his goal all along), also Aliza (as she's lost enough weight Hunter now finds her attractive), also Brenna and Catherine for obvious reasons. Hunter initially tries to corrupt Sterling the same way as Andrew but that fails (see What If number 3 to see the alternate timeline where Sterling agrees).
Sterling later finds his father's diary/letter to him and learns his dad wasn't really a bad dude and felt guilt about his crap treatment of Sterling. He warns Sterling to watch out for Hunter (and Drew) and protect his family from them becoming mind-broken incest sluts. Oh the irony.