An example would be a parent who doesn't want any gender-related issue to be discussed in the school.

Are they inherently flawed and inherently hateful individuals?

Yes, for the reason Dirt_Possum stayed below. They have a responsibility to properly educate themselves on issues that effect their children or decisions they may make that impact other people's children.

Not wanting to explore issues like gender or race is part of why certain forms of bigotry have proven so persistent.