Not going to touch the abortion analogy, but I did stop eating meat partly on the basis of ethical reasons I had laughed at for most my life.
Politics and religion: my personal beliefs haven't undergone any big changes post-college, but I have come to see even very conservative worldviews as much more understandable and legitimate than I once did.
And not in a patronizing "oh, I get how a person's upbringing might make them hold those incorrect beliefs." More an understanding that different people and societies come to emphasize different values for historically important reasons. One of the best books on the topic is The Righteous Mind by Jonathan Haidt. Won't give the whole synopsis, but it has helped me better see the rational in opinions that I may have previously dismissed as selfish/crazy/ignorant/etc.
I also like mustard more than ketchup now.