OP hasn't specified the age of their kids, so I don't know. I was talking about their kids, if anything.
Well, you said the conversations are also mature therefore the visual reduction in gore will not fulfill a purpose, and they should move onto another game. I'd like to say this goes away with age, but visual comprehension and written comprehension are very different things.
A child watching a sex scene versus reading this dialog from Firefly:
Mal : Whoa, hey. Flesh. Um... Saffron... i-it-it ain't a question of pleasing me. It's more a question of what's... um... of what's morally right.
Saffron : I do know my Bible sir. "On the night of their betrothal, the wife shall open to the man as the furrow to the plow and he shall work in her, in and again, 'til she bring him to his fall and rest him then upon the sweat of her breast."
Mal : Whoa, good Bible.
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Im guessing the sex scene would be a lot more consumable. The number of games I have thought of as Ive gotten older where I went "oh, man I had no idea what that meant when I played that as a kid, thats hilarious" is, well, most of them. Adults are making these things and kids don't have a narrative for it. You don't, however, have to be very old to know what a naked body or someone's head being forcibly removed from their body is.
If we go by ESRB 17+ ratings and children are 16 year olds and below and hold 16 year olds to the same mental ceiling at a 10 year old, that swathe we are now cutting into becomes a hot debated topic. We have Eminem in the early 2000s testifying to congress and them making laws to make it so you can't say whatever you want to in songs. This isn't a new thing, but it isn't an old one either. As gaming continues to evolve and you might be a 50 year old man playing multiplayer watching a sex scene with a 17 year old girl that you dont know the concept of choice and consent come into play. You, a 50 year old man, have no issue watching the sex. You a 17 year old girl, have no issue watchin the sex. You both might find it inappropriate in your playthrough together, however.
The concepts of adolescence, childhood, and maturity shift on situational contexts as well as along just the age & development axis. So, when we realize how much is out there that could influence or drive a decision on how and in what nature someone might want to experience something you have to ask - how much effort are we talking about to do this? If it isn't a lot of effort, then I guess I am still trying to figure out what the opposition is other than "lol, g4m3r lyf old man, dont have kids looser lolol suck my M rating"