I agree with you that relationships move at different speeds. Still, my thought or argument is based on L&P's thoughts that incestuous liaison, as you put it, can only be accomplished if the person, Sophia, is corrupted. However, if we compare the two corruption stories so far with Dylan and Ellie, we can see very little corruption based on the story's context and not the point system he uses with Ellie. Also, you have to consider how the reader chose their path. Are they skipping paths to their liking or are they playing it unchained? You can definitely see the level of corruption she has if you play the novel unchained.
I'm not asking for a one-to-one ratio on who gets what and when, as that would make very little sense. Instead, I'm looking at how L&P should have applied that statement to the story. Right now, this is how I see the character progression using a simplistic line with Sophia.
Currently:
Liam > Ellie > Female Cast (Corruption) > or = Patricia > or = Male Cast (Aiden) (Corruption) > Sam > or = Dylan
IMO, it should look more like this based on L&P's comment about incest, which factors in the slight female advantage.
Liam > Female Cast (Corruption) > Ellie and Patricia > or = Male Cast (Aiden) (Corruption) > Sam > or = Dylan
If corruption is the driving force behind the incestual part, it won't make sense where Ellie ended up in the story. Right now, it feels that the incestual part for corruption is only being applied to Dylan and not really Ellie.