She is an ignorant wastelander, and only knows as much as any wastelander. As far as they, and therefore she, knows, synths are programmed to lie and infiltrate and kill us all. If your opponent in a war is robots who pose as you, naturally you would want to squash them like roaches, as she puts it.
But even so, we see her attitude change when she meets Glory. She likes glory, and even says positive things about her. When she meets a synth that isn't posing as someone else, and is just a person, she likes them.
She dislikes helping Danse because helping Danse coincides with her "don't risk yourself for other people" stance. Why jeopardize your personal safety, and your position within the brotherhood, for this guy? Thus, she wants to kill Danse. Plus, she sees Danse as an infiltrator, and may not understand the difference between a free synth and a rootin' tootin' synth.
I evacuated the toot, I helped the synths with their rebellion, and I even supplied them and encouraged them and stuff. At every opportunity, I help synths. I told Des that sure, I would die for someone even if they were a synth (but the option that said anyone, regardless of synth or not). After all this, Cait never left. So I'm not convinced by your "she wants to genocide them" hyperbole. She is a wastelander with wastelander impressions and knowledge of synths.
>something or someone
>someone
user, I'd prefer if we actually talk about events in the game.
Which reminds me, Cait has in fact never killed a cat. There is no cat blood on Cait's hands. She approves when you do it, but we don't know why. My theory, about her own life experiences making her jaded and have a terrible view of people, and thinking this lesson serves these kids better than coddling them, makes a lot of sense. People actually think that way in real life. Since, people actually do this in real life, I'm more inclined to believe this is the case.
Why do you think being a psycho is more likely?