Actually, Tupac did eventually meet his biological father: Billy (William) Garland. After Tupac was shot five times on November 30, 1994, in New York, he met his father in the hospital. Before this, he had thought that his real father was dead. Tupac later would say "I thought my father was dead all my life. After I got shot, I looked up there was this nigga that looked just like me. And he was my father; that's when I found out. We still didn't take no blood test but the nigga looked just like me and the other nigga's dead so now I feel that I'm past the father stage."
After Tupac's death, Afeni and Billy sent a sample of Tupac's blood to Long Beach Genetics, who did the DNA testing, and the probability of Afeni and Billy being Tupac's parents was 99.97% - a match.
Tupac's father figures ("Tupac's fathers"):
~Tupac's stepfather, Mutulu Shakur, was arrested in 1986 for allegedly planning and executing the 1981 "Brinks Robbery" where an armored car was robbed and two New York policemen and a binks gaurd were killed; he is currently serving out his 60-year jail sentence.
~Tupac's godfather, a gangster by the name of Geronimo Pratt, was also jailed for nearly the entirety of Tupac's life; he was recently released after Tupac's death after serving 27 years of a 25-to-life murder sentence.
~Legs - got Afeni (Tupac's mother) addicted to crack