One of the primary techniques used by law enforcement to deanonymize people they can't technically trace is simply data mining and profiling. People give away enough bits of information about themselves over long enough a period of time, law enforcement gathers all these bits and makes a profile of the person, and eventually the profile they make is good enough for them to determine who the person is. Saying one or two little things about yourself is probably no big deal in itself, but if you do this enough times eventually you will probably deanonymize yourself.