Tbh, I think Chris's moral compass is kinda not entirely known. Like we don't know the upper/lower limits of where he draws the line at this juncture of the game's current update.
Perhaps he's into sticking his dick into whatever (semi-attractive) adult female he wants to bang (family or no family), and he doesn't have any qualms nor restrictions on that.
OR perhaps he does have a conscience and chooses not to draw the line with people in his family. I think he's kinda unhinged/unpredictable in his mannerisms, so I don't think anything is really beneath him to want to experiment with based on my personal opinions of him. But who knows tbh?