Obama was born in august 1961
1961 - 1942 = 20 years
Obama is a Natural born american
http://en.wikipedia.org/wiki/Ann_Dunham
Stanley (S.) Ann Dunham Soetoro (November 29, 1942 – November 7, 1995), known as (S.) Ann Dunham, and later as (S.) Ann Sutoro[1] was the mother of United States Senator and presidential candidate Barack Obama.[2] Dunham was an anthropologist who later specialized in rural development. Born in Kansas, Dunham attended high school near Seattle, Washington and spent most of her adult life in Hawaii.