Are there tabboos? Of course. There are still many cultural norms and tabboos, even if you may be thinking of a modern perspective where there are many different groups and they don’t all agree what they are. Ask any conservative and/or religious people, and they’ll give you quite a list.
Even amongst secular modern Western people, there are some tabboos that are generally agreed upon, if that’s what you’re asking.
For examples in addition to those people already mentioned: cannibalism, feeding humans to animals, unconventional forms of self-mutilation, unauthorized application of violence, sabotage, theft.
My own biggest tabboo is doing anything that would make me think unforgivably badly about myself. I also consider destruction of ecosystems and wildlife, some of the worst and most disturbing things anyone can do.