Faolyn
(she/her)
Unless you're joking, it doesn't sound like you're actually familiar with it.I am familiar with the one drop rule, it's on all the hot sauce bottles.
In case you're not joking and honestly don't know what it means... if a white person could be said to have any amount of non-white heritage, even generations back, then you weren't considered white. You would be subject to laws that affected non-white people, if others knew about it, and may not be able to get the jobs you want, marry whom you wanted, or live where you wanted. You could lose friends and be ostracized from your extended family.
So, trivialize a player's legitimate, out-of-character phobia and mock the player all at the same time?As to your arachnophobia player, I would then introduce a spider who'd sympathize with her. Upon learning of her phobia he would tell her, "Sorry, but this is what I am. What I resent is your stereotyping me, and I would appreciate your treating me as an individual."
What you're saying would work only if it were an in-character phobia, like, they took the Phobia disadvantage and got points for it or something. If it's an out-of-character phobia, then what you're saying is heartless, clumsy, ill-intentioned, and not even remotely going to help the player one bit. Pro tip: you are not a therapist (and if you are, you shouldn't be gaming with your clients), and you are not qualified to help anyone get over their fears.