Yes, most of them are of mixed origins. However:
"At the dawn of the 21st century, the idea of 'race'—the belief that the peoples of the world can be organized into biologically distinctive groups, each with their own physical, social, and intellectual characteristics—is understood by most natural and social scientists to be an unsound concept. The way scientists think about 'race' today, after all, is different than it was in the wake of the Civil Rights Movement when some promoted black genetic inferiority as an argument against egalitarian social and economic policy, and certainly different than one or two centuries ago as scientific justifications for slavery and later Jim Crow were articulated. In other words, 'race,' its scientific meaning seemingly drawn from the visual and genetic cues of human diversity, is an idea with a measurable past, identifiable present, and uncertain future. These changes are influenced by a range of variables including geography, politics, culture, science, and economics.
Today, despite the growing consensus among scientists that race is not, in fact, a useful classificatory tool, an understanding of human difference and diversity remains a hallmark of contemporary scientific practice, and thus presents a seeming contradiction—how can one study human difference without talking about 'race'? On the one hand, beginning in the 1930s, advances in population genetics and evolutionary biology led many to conclude that the race concept was not a particularly useful or accurate marker of biological difference. By the 1970s, many prominent biologists, including the geneticists Richard Lewontin and L. Luca Cavalli-Sforza, came to see the race concept as a deeply flawed way to organize human genetic diversity that is inseparable from the social prejudices about human difference that spawned the concept in the 18th century and have accompanied its meaning since. Historians and social scientists believe that 'race' is socially constructed, meaning that the biological meaning of race has been constrained by the social context in which 'racial' research has taken place.
On the other hand, because studying genetic differences can improve our understanding of human evolution, disease, and development, the relationship between genetics and human diversity remains an ongoing area of scientific inquiry. The challenge has been to develop a new scientific terminology and methodology that finds meaning in the study of human difference without recapitulating outmoded and 'racist' notions often associated with the concept of 'race' itself. Some scientists have developed novel ways to measure difference between various human populations, including using ancestry, ethnicity, and population as replacements or surrogates for race. Others, however, remain steadfast in their belief that technological and methodological improvements now allow an examination of 'racial' difference with increasing precision that is disconnected from any social prejudices."