I have not participated....might though,, although I have a decent idea where great grandparents came from....northern europe,...England, Denmark, Germany.
For men, the NG project will trace back your y-chromosome DNA (your father's father's father's father's father's father's father's father's father's father's father's father... etc.); for women, it traces their mitochondrial x-chromosome DNA.
Other services will trace BOTH your y and x chromosomes, but they're pricier.
