Sure, I know a good number of progressive folks raised by progressive families. But I know *even more* fucking hardcore activists raised by right-cult weirdoes.
I remember the kids in college that came from homeschooling or strict religious backgrounds getting their first taste of freedom. Amazing to behold. College doesn't "indoctrinate" students to liberalism. Exposure to the real world does. Reality has a strong liberal bias.
The Great Replacement Theory is gaining traction. As for outbreeding the leftists, I always thought it was the social security loving leftists with hundreds of kids living on benefits that were the problem.