Bad Words

Okay, this has been bugging me for a long time now.
What makes bad words bad? Are they inherently bad? Do the meaning/s of such words contribute to their badness? Or are they bad because we were told since birth that they are bad?
If bad words are bad in themselves, what is in them that makes them inherently bad? What separates them from other words that seem to not have inherent badness?

If the meaning/s of bad words make them bad, then how come some of their synonyms aren't considered bad words? Take feces for example. Feces, along with its synonyms poop, shit, and crap all mean solid waste matter excreted by the human body. But of the four, only shit is considered as a bad word! Why? Why? They all mean the same.

Most likely, these words are bad because we are told as little children that bad words are bad.
But then again, what do these words possess that prompted society to label them as "bad", thus programming children not to say such words?
The question goes on and on.