What is this trend about being 'mixed race'?

[Reedy]

So I'm mixed race, my mother is white English and my father is black Caribbean from one of the islands called Dominica. I've noticed recently there seems to be some trend about being 'mixed race', and some of these people claiming to be mixed race just aren't. For example on instagram/twitter, in peoples bio's they will say 'mixed race' like it automatically means they are pretty?
Too many people generalise mixed race people to be pretty, I admit most of the other mixed race people I have seen are pretty and the boys are handsome but we are no different to any other race. It really really annoys me when people say they are mixed because they are 'half spanish and half irish' yet they are white. I've already looked it up and to be classed as 'mixed race' you have to have one parent of colour, it doesn't count if they are different nationalities.
I don't want to sound like a snob but I get compliments, I get attention, and I am classed as 'hot' at my school but I am humble. I don't boast about my heritage or anything. This year I have made 2 black friends and they say I'm the first mixed race girl they have gotten along with because the others are stuck up because they think their race makes them beautiful.
It's like the whole TeamLightSkin vs. TeamDarkSkin. Why is this?