Generally, taboos exist in all languages and cultures of the world but with varying degrees. Taboos are violations to ethical, moral and social norms of society. To whatan an extent people exchange and use taboos in your culture?
Since I'm from Germany, the biggest taboo in terms of speech (in a political way) would be a contempt of the Holocaust during World War 2. It's not that you aren't allowed to talk about, but especially in recent times, with a lot of right wing and right-extremist populism, some people try to revise the German role and cruelties during that time, which is a big problem.
Even if the following generations aren't directly related to what happend during WW2, in my opinion we still have (and should have) the responsibility to recognize what happend during that time and make sure, that this will never happen again. What I call responsibility here is not only some kind of morality, but an ethical responsibility as well. Not only regarding the past, but also regarding the future, to prove responsible to have learned, that we all are (always potentially) at risk to turn into facism (again).
When we really have learned from this catastrophy, our ethical responsibility lies especially in proving that we have learned, to make sure that this won't happen again and to always remember, that this potential risk can't be eliminated.
I rather thought taboos were things we didn't use? Here in the UK there's so few general ones I couldn't name one. But particular ones are everywhere! You have to work out the other person's views on a potentially controversial subject before you say anything important about it. We have loads of racists, sexists, anti-europeans, anti-americans, anti-semites, anti or pro anything you like. But keep it to yourself until you're amongst the like-minded on this issue!