Surprises from DNA: Families' ancient roots revealed by their genes

All humans are 99.9% alike, according to Wits University education specialist Ian McKay.

"The 'differences' between races do not really exist; they are just things in our head," he said.

McKay was speaking at the Wits Origins Centre during a DNA ancestry-testing workshop on Saturday.

The testing determines where ancestors lived but gives no data on genealogy and family trees.

Nelson Mandela, Desmond Tutu, Leon Schuster, comedian Marc Lottering and radio presenter Jeremy Mansfield are some of the famous South Africans who have tested and have made their results public.

Rajeshree Mahabeer, a National Health Laboratory Service medical scientist, said most people who took the test were complementing their genealogy research, or curious to know about their roots.

"They feel this might give them that little bit of information, that little bit of connection to where their ancestors may have come from. It links them to something."

The laboratory does two types of DNA ancestry testing - mitochondrial and Y chromosome.

Only women pass down mitochondrial DNA to the next generation whereas the Y chromosome test determines maternal or paternal haplogroup, a combination of numbers and letters that indicate DNA mutation.

The number combination is used to determine where ancestors originated.

Haplogroups have been mapped across the world.

McKay said: "We have the most variation [of haplogroups] here in Africa, which is good evidence that humans originate in Africa."

Three people who volunteered for testing told The Times why.

Tess Young said her ancestors came to South Africa from southern China in the 1930s.

"I am convinced I have Italian blood in me because I like pasta so much."

Mateenah Hunter said when she heard tests were being done at Wits she thought it might help her make sense of her mixed family background.

"I like the idea of having a rough idea of my ancestry."

Kath Robins said a friend had her DNA sent overseas for testing and "it came back [saying] she was Khoisan".