Someone from Guinea (could you call it Guinea-Conakry?)
is also Guinean.
There are two different countries in Africa. One is Guinea-Bissau (its capital is Bissau). The other is called Guinea (its capital is Conakry, but the country itself is usually not called Guinea-Conakry).
Apparently, inhabitants of either country are called Guineans.
But it's amazing that the DNA outfit could establish a unique signature for Guinea-Bissau as opposed to Guinea or Senegal.
When I first looked at your picture, I thought it might have been a guinea pig -- possibly related to this area, possibly not....
Guinea pig
1664, native to South America and is so called either because it was first brought back to Britain aboard Guinea-men, ships that plied the triangle trade between England, Guinea, and South America; or from confusion of Guinea (q.v.) with the South American region of Guyana. (Online Etymology Dictionary).