Researchers have used DNA submitted to one of all the services that offer people to find out more about their roots.
DNA from over 50,000 Americans has been analyzed.
Research shows that African Americans in the United States have an average of 70 percent of their genes from ancestors who were captured in Africa and shipped as slaves between the 16th and 1800s.
During these years, an estimated 12.5 million people were forced into slavery.
Women have made a bigger impression
But despite the fact that most of the slaves on the ships were men, around 60 percent, the genes of the female ancestors have given twice as large an impression in the descendants' genome.
According to the researchers, this is partly due to the fact that white slave owners often raped female slaves.
In the World of Science, African-American Tyquine Golden gets the opportunity to do a DNA test to find out more about her roots.
- I do not want to avoid the truth, no matter how horrible it may be, he says.
Tyquine Golden's test results show that he is 80 percent from West Africa and 20 percent from Ireland and the United Kingdom.
But according to the researchers, he is far from alone in having DNA that shows traces from Europe.
Want to know more about what our DNA can reveal? See the whole World of Science on Monday 5 April at 20.00 on SVT2 or on SVT Play.