It's not about responding. It's about responding the way you do. You respond like a nerve was struck and you have no way to dispute it other than doing the ol' "haha you're the only unique one amirite everyone else is sheeple," shtick.
But I'm not unique. Everyone succumbs to it. The difference is how much you succumb to it and whether you can recognize it in yourself.
You respond defensively, personally. You could even just say you don't agree, but the way you respond reeks of subconscious discomfort with the subject matter, like a drugs addict called out on their unhealthy vices.
Do with that knowledge what you will.
As for mixed race people? Like I said, it doesn't just affect them. It's just worse for them since rather than partaking in multiple cultures, they're generally stuck between them, unable to integrate parts of their own culture to shape some of their own identity. Mix that with current day consumerism to fill the void and it just gets worse. But you're right, the problem isn't being mixed race, it's the increasing frequency with which people of any ethnicity adopt product and corporation as a part of their identity, which, as I said, we all succumb to to some extent. Being mixed race just compounds it because there is a bigger gap to fill.