generalize about (someone or something)
To consider a specific situation in broad or vague terms. Quit generalizing about their divorce—none of us know what's really going on there. We shouldn't generalize about a situation as complicated as healthcare.
generalize about someone or something
and generalize on someone or somethingto interpret someone or something in very general terms. Sometimes it isn't wise to generalize about a complicated issue. She is very complex and it is difficult to generalize on her.