Microsoft's bot (Tay) learned as people talked with it. People took advantage of that and basically attacked it with racist things which meant it ended up learning to be a racist.
My point was that, parenting 101 is not to model behaviour we don't want to see in our kids (don't point to twitter if you want a polite non-racist AI bot!).
Thinking about it now, this is deeper... There's a fear that AI will take over the world, use weapons in unethical ways, say one thing and do another, etc... If we use news channel and politicians debates to teach AI, I'm afraid that this is exactly what we're going to get!
It's pretty well established that modern AI's main contribution is (a) massively larger datasets, (b) algorithms and technology to handle those massively larger datasets, (c) boring but important parameter tuning.