Physically, you can see race. Skin color is the most predominant feature of race, but it's a little deeper than just that - noses, ears, hair, eyes, etc. all are a part of it. As all of these are inherited features, people more closely related together - those of the same race - will appear more similar to each other than those of a different race. As a result, people will come together and categorize that into race, and in so doing, they are creating arbitrary boundaries where a race "begins" and "ends", and they are often attaching meanings not inherent among the people they are categorizing (because when you think collectively, it's easy to think that anyone in the same category is very much the same or similar in ways beyond simple appearance, particularly if they also share a culture together as that has naturally came with race too in the past and still so to some extent today). This is why race is socially constructed, at least in how we think of it, and by calling race a social construct, it doesn't necessarily deny the reality of it that exists in our genetic makeup.
A social construct is anything created by society that isn't inherent among individuals. Society, by its very nature, is a collective. No individual decides it, but individuals together decide it, and usually they come to this decision based on some consensus of the reality they are surrounded with.
What race you belong to is not decided by you as an individual but by society. White privilege theory says that those with power are the ones who define where the arbitrary "boundaries" of race are and thus where it begins and ends, and they enforce that onto everyone else. In other words, you are told what race you are by society and that's the race you will identify with. You can be black according to society and identify with Asians, but good luck getting anyone else to do that. You will be treated as black no matter how Asian you perceive yourself to be. This is only possible because race is a collective definition, not an individual one so much. And then there is also the fact that race does have a real basis to it, as insignificant as it may be.
A prime example are many blacks and whites of mixed origins who will often consciously select the category which society and people around them are most willing to accept. Regardless of they actual ancestry they will tend to select the social groups most ready and willing to accept them
During the worst days of slavery and segregation many people of mixed ancestry who could appear "white" moved North or West, changed their names and mingled seamlessly and undetected among the white population. These people often married whites and thus after a few generations became undistingishable from other whites.
^ these muhfuckas, man...
i would still be white because of the job opportunities that are available
lawl
I'd stay black.
i'd keep the race i have