Yes they can. There is no objective measurement of 'race'. Why? Because it doesn't actually exist. Other than in people's minds. Maybe so-called "Black" Americans feel no connection to, and do not consider themselves, "Black". They actually feel and act 'White'. You know: Oreo? Or Yellow people who are 'Banana's'? Or so-called White WannaBe's? There is no real 'race'. What we do have are environmental pressures on isolated populations that have selected for some phenotypes: Including behavioral, height, mental aptitude, even RBC shape/protein expression. It doesn't mean that ANY human ANYWHERE cannot be born with a similar phenotype, only that some humans were selected and other died when they didn't have said phenotype/s. Humans who migrated north probably died if they didn't plan for the winters. If they didn't work in communities. Humans who were small and skinny died on the open waters traveling island to island (or failed to reproduce at least). Others grew smaller (as animals tend to favor one or the other on islands). Humans who didn't have light complexion didn't produce enough vitamin D. Humans subjected to ice-glare were selected for epicanthal folded eyes. Humans who lived in the far north were more rounded to reduce surface area. Etc.... Pretending this didn't happen is asinine.