Why do opposites attract, and why does it seem those relationships often work well it seems?

Do you think it just keeps things interesting to some people?? I wonder because my mom was raised going to church constantly, and by the time she was a teenager she was teaching the Sunday school there every weekend and Wednesday nights. She doesn't cuss, drink alcohol, smoke or do anything "bad" at all, and she was just 100% Christian. Then my dad has smoked weed, done mushrooms/acid back in the 70s when he was just a teen. He grew up in the "Hollywood" crowd, my grandparents raised him the God is a figment of people's imagination and the Bible/sins are just a way to control people. He's read the Bible, Qu'ran, knows everything about Judaism, etc he can debate things in the Bible with my mom, and he's obsessed with science, astronomy, evolution, etc.... my mom doesn't understand/"get" any of it because it goes against her religion (but she tries to lol). Still, my parents have been together since they were both 19, and now they are both 50. How is it that these types of relationships work so well sometimes?? I think its cute, but I would never guess to put these types together. I sometimes wonder what it'd be like to maybe date a guy opposite of me in some ways too, because I grew up in a household where I got to learn/see both sides. I like that. What do you think???