To start just encourage empathy, generosity, collectivism, and a desire to learn. Eventually when they start to notice liberal programming just simply debunk it. When they here about billionaires in the news or from peers tell them about how much exploitation, greed, and luck got them to have that wealth. Point out how many better things could be done with it. If you see homeless people in the street tell them about the injustice of the system that brought them there. How there are many homes that they could live in, but the landowners are too greedy to let them. Just frequently talk about social issues in your household and the children will listen and try to understand, because as a parent you’re interesting to them, they might even ask questions. I could go on for a while, but I hope this helpful.

PS I’m actually a teen and this is what my socdem parents did for me. I’m sure the values they instilled are a major reason why I’m a commie today.

I'm not a parent but i think it just boils down to giving them quality attention and having good communication with them. For the god of love don't give them a tablet/phone to keep them entertained when they're young.

Encourage reading!!! If my parents weren’t so positive about my love of reading at a young age (including Harry Potter lol) I DEFINITELY wouldn’t give enough of a shit about intellectual endeavors or political awareness. I would be a Bernie Bro AT BEST, probably a Centrist who doesn’t care. Also obviously raising a child like a human being, allowing them to have fun, obv not saying you would do this lol, but for example, don’t force your kids to study Marxism-Leninism at a young age, they’ll resent it