I've heard something from someone and that idea has been "corrupting" mind.

Example I would hear from someone: the sky is actually blue.
And even though I know it's not true the fact that I heard it has be constantly questioning if that is true.
I keep pushing the idea back by saying either that it's not true or it's impossible but the idea implanted into my mind keeps me thinking it.

This is happended multiple times in my life whenever a parent of mines would say something stupid and I know it's not true but the fact that they put the illogical idea in my mind it's almost like I can't stop the idea. 

Do I suffer from mental illness or trauma? Yes. Some strong enough to destroy my empathy towards others.

This could be because I have little trust in my reality. 

Or I'm not strong enough to believe in the truth anymore.