Biology determines many aspects of human variation, and for the last few hundred years it was assumed that race was synonymous with this biological determination. However, now that science has advanced we are beginning to see the bigger picture, where skin color was determined based upon where a group of people lived over hundreds or thousands of years. It was an adaptation to those locations, a means for humans to survive in varying climates and levels of sun. Race, by extension, is simply a means of saying that one person looks different than another person: it is based on observable traits that have no genetic influence of their own. We can see this in twins where one twin is white and the other twin is black.
In today’s world, not all groups of people are locked to the location of their ancestors. People move around, and the subtle variations of skin color can be seen in a full spectrum of shades in major cities. Naturally, some people of different skin colors come together and have children. If race was part of a genotype, and not a phenotype, children of these couples who are twins (and share most of their genetic code) should appear the same; their skin color should not be so radically different. If race was the cause of biological variation, then the mixing of a ‘white race’ and a ‘black race’ should come up with a ‘mixed race’ that would appear similarly in twins, even if they are fraternal rather than identical.
However, race is not a genotype, and does not have any sway over biological variation. Rather than being a cause of biological variation, it is simply a result; a phenotype that is determined by environment as much as it is a reflection of genes. Twins that have one white twin and one black twin show this; by any outside determination, someone would classify the white twin as being part of a ‘white race’ while the black twin would be classified as part of a ‘black race,’ when in reality they are both white and black. Their skin color is wholly arbitrary and shows that race has no bearing on biological variation, the same way that someone’s weight has no bearing on biological variation.