I got more politically progressive when I had kids. It's the opposite for some, but I really started paying attention to the world we were making them inherit, and realized how corrupt it had been all along. I had bought into a lot of myths most of my life. Things got real pretty quick.
There was one guy I met on one of the early AOL boards who kept talking about how deeply religious and conservative the country was, and how there was going to be a backlash. It was the Clinton years and I thought he was being over-dramatic --- social progress was slow but irreversible I thought. He was right. I was wrong. Pretty sure I'm not the only one surprised by America 2021.
I've had HuskerBoard posters correct me on some of my favorite liberal talking points by directing me to credible sources. This ruined some of my best arguments, but I'm grateful for it. I never repeat misinformation and correct it wherever I can. It tempers but rarely changes my opinions on the larger issue. These posters were right and I was wrong. They could have been a$$h@!es about it, but I mostly remember them contradicting my claim and proving it. Touche.
The New Yorker, The Atlantic, NPR, and other sources folks might deem biased have also changed my mind about folks like The Clintons, Barack Obama, and Jesse Jackson, and issues like oil pipelines, GMOs, and media mishandling of major news stories, with in-depth reporting that runs counter to the liberal party line. When someone who shares my basic ideology isn't afraid to uncover inconvenient facts, it definitely changes my opinion. Still, there's a good chance I already had a gut feeling.