Similar to JaysThoughts, I am in my mid-thirties, and have not lived with my parents for quite a long time. I do, however, maintain a very good relationship with them. When I did live with my parents, I chose to engage with them based in their particular perspectives, for fear of losing their support while I needed it (though in truth and in hindsight, my parents would not have kicked me out for crimethink). The rest of this post has to do with how I do (and have) engaged with them, if that might be of any help.
My parents are actually exactly what parents ought to be, at least in their relationship with me, they love and support me, though they don't always agree with me. They have also always allowed me the space to do my own thing and find myself, which is a privilege not everyone has.
We don't talk politics that much, but they know what my perspective is on things, for the most part, and they have helped with particular projects in the past, if in very minor ways. The one time I have been arrested (at an anti-RNC action) they were who I called from jail and, to my surprise, were glad I'd been involved in trying to escalate the confrontation.
My mom is a Democrat. She seems to view my my politics as an extreme liberal/progressivism with some troubling opinions on the value of property, the sanctity of cops health and wellness, and a troublingly critical view of the role of government in providing for our needs. She is generally more willing to talk politics with me, but I find we can only go so deep, and then it hits a wall where she (or I) change the subject.
My dad was, growing up, a republican, in my young adulthood, he started to shift towards identifying as an independent. He retains the hallmarks of conservatism while opposing attacks on the social safety-net that are waged by the right. He and I speak less of politics, but he is far more open to me presenting ideas that challenge his frame of thinking (which, I actually think was set ajar by the ascendence of the pre-tea party types. My dad is conservative, but he recognizes crazy people when he sees them.) It is my father who seems to sense that capitalism and democracy are a rigged system, doomed to fail.