dollars to donuts says 0 shares no genetic material with this woman
She doesn't.
From Wiki
Sarah Onyango Obama
Third wife of Obama's paternal grandfather, born< 1922.[58] She is known for short as Sarah Obama and is sometimes referred to as Sarah Ogwel, Sarah Hussein Obama or Sarah Anyango Obama.[75] She lives in Nyang’oma Kogelo village, 30 miles west of western Kenya's main town, Kisumu, on the edge of Lake Victoria.[76][77] (She should not be confused with her stepdaughter of the same name, Sarah Obama, a daughter of Onyango's second wife, Akumu.)[78]
Although she is not a blood relation, Barack Obama calls her "Granny Sarah".[75][79] Sarah, who speaks Luo and only a few words of English, communicates with President Obama through an interpreter.