Which members of their families or communities got "pretended out of existence" in the past?

That's the kind of person that might get born into the family again. And then what's going to happen???

When a particular GrandX eventually gets another humane being in the family whose "other" genetics or neurodiversity or life-altering experience is not something that everyone in the younger generation feels good about ignoring 

or pretending is unimportant to acknowledge 

or simply does not exist, 

how well will the particular GrandX be able to handle the situation?

By looking more discriminatory towards the different one, as was the case with certain kinds of people in their society in the past? 

Or will they not want to look so extra discriminatory?