You cannot control what someone does or doesn't believe but you can teach ways to deal with an abundance of information and political agendas.
To teach a person to correctly look behind the curtain without falling into conspiracy is the greatest gift. My parents failed to do so because they hated discussing topics in a neutral way. They also knew nothing about philosophy or propaganda.
Same way parents can teach stoic wisdom without raising an emotionless kid. Same way we can teach morals and responsibilities without the need of any religion.
I would summarize that parents just should be parents. Kids mirror parents and being calm and focused is so important. My parents were and are always angry and this got imprinted in my subconsciousness, which sucks. (Bully target) Thankful most people grow up fast school age.
For example last weekend I talked to my cousin about some good news sites, that are as unbiased as possible. (In Germany we thankfully have independent press). I think it's important to grow up not drifting in desperation of "all news fake. Voting doesn't matter", it makes one feel helpless and thats the last thing a kid should have to endure.
Understanding how to identify wrong information, as the fake news they are, with examples and exposition is so important.