When Does Predictive Technology Become Unethical?

Machine learning can ascertain a lot about you -- including some of your most sensitive information. For instance, it can predict your sexual orientation, whether you're pregnant, whether you'll quit your job, and whether you're likely to die soon. Researchers can predict race based on Facebook likes, and officials in China use facial recognition to identify and track the Uighurs, a minority ethnic group. Now, do the machines actually "know" these things about you, or are they only making informed guesses? And, if they're making an inference about you, just the same as any human you know might do, is there really anything wrong with them being so astute?