Washington - The idea of race is not reflected in a person's genes, Brazilian researchers said on Monday, confirming what scientists have long said - that race has no meaning genetically.

The researchers looked at one of the most racially mixed populations in the world for their study, which found there was no way to look at someone's genes and determine his or her race. Brazilians include people of European, African and Indian, or Amerindian, descent.

"There is wide agreement among anthropologists and human geneticists that, from a biological standpoint, human races do not exist," Sergio Pena and colleagues wrote in the Proceedings of the National Academy of Sciences.

"Races exist as social constructs," they said.

They found 10 gene variations that could reliably tell people apart genetically, but the differences did not have anything to do with physical characteristics such as skin or hair colour.

Maternal DNA suggested that even "white" people had, on average, 33 percent of genes that were of Amerindian ancestry and 28 percent African. - Reuters