Pretty much any of those would be allowed in my games except for Beastiality and Necrophillia. (*Although I don't see anything wrong with an NPC having the Lich Loved feat from 3.5. But then that would be more of a tragic situation that happened to said NPC and may need the PC's help in getting out of that.)
Rape/Molestation/Pedophilia: Well that's another three things added to the list of Reasons the PC's need to kick the ass of said NPC. This also would include Soldiers/Mercenaries who view Maidens as Spoils of War.
Slavery/Bigoty: Well despite WoTC's views towards things and such, the world isn't a wonderful place where everybody gets along. So the Dwarves are gonna make their remarks about Elves, The Sun/Grey Elves are gonna have their snooty snouts and mighty attitudes, and Humans are gonna view Orcs and Drows in a negative light due to their reputations. But the Dwarves still insist they aren't racist, they just Grudge. And Grudge they do.
Some races are also gonna try to overcome other species in unpleasant ways.
Incest/Cannibalism: The usual crazy NPC family trope or some other not so positive character.
Blasphemy: Depends on how religion is handled in the campaign. Depending on who is comitting it, it can be a negative thing or a good thing if the PCs are like opposed to the religious practices of Lolth or Erythnul, the god of Slaughter.(And despite real world views, is still a form of Taboo in some way, shape, or form.) Watch out for the Lawful Stupid Paladin
Thievery/Murder: I mean Rogues gonna rogue. Thieves Guilds and all. And well murder is something most bad guys like to do, especially towards the PCs.
Torture: Bad guy/Lawful Stupid Paladin 101.
None: I don't know, I didn't choose that option.
Book of Erotic Fantasy: Technically this is another Taboo as well: the idea of sex. Happening in games or with characters during sessions. Yes this could also be a subset of the Rape/Molestation/Pedophilia, but those are the Chaotic Evil/Not Kosher route of the idea. I mean like legit characters having sex, a race having a sexual history, or whatever and there isn't a rape fantasy happening or some other messed up hits. Some people that play DND may not want the Hentai clip to play during the session and instead prefer the fade to black. And it would be another thing that would have to be discussed with players before hand or for the DM to know whether stuff like that is okay at the table and not. Everybody is different. For me, I'd allow it. As long as everybody was comfortable with it or there was no problems. And especially no Rape/Molestation/Pedophilia. If that happens at the table, I'm gonna kick your ass out, or make sure the guilty characters get hit by a D20 Powered Paladin Smite from a NPC paladin nearby, because I said so, and then kick em out.(Said Smite has Auto-Advantage on rolling a Crit Hit that confirms on a 10-20 dice roll).
Note stuff like this wouldn't be happening 24/7 in sessions.