The 18-year-old runner's father, Jacob, told the Sowetan newspaper: "She is my little girl. ... I raised her and I have never doubted her gender. She is a woman and I can repeat that a million times."
Semenya dominated her rivals to win the 800 on Wednesday despite revelations that surfaced earlier in the day that she was undergoing a gender test. Her dramatic improvement in the 800 and 1,5000, muscular build and deep voice sparked speculation about her gender.
"She said to me she doesn't see what the big deal is all about," South Africa team manager Phiwe Mlangeni-Tsholetsane said Thursday. "She believes it is God given talent and she will exercise it."
Mlangeni-Tsholetsane said Semenya was thrilled about winning the race and picking up her first world title.
"She was over the moon," Mlangeni-Tsholetsane said.
Semenya wasn't the only one wondering what all the fuss was about.
Semenya's paternal grandmother, Maputhi Sekgala, said the controversy "doesn't bother me that much because I know she's a woman."
"What can I do when they call her a man, when she's really not a man? It is God who made her look that way," Sekgala told the South African daily The Times.
About three weeks ago, the IAAF asked the South African athletics federation to conduct the gender test after Semenya burst onto the scene by posting a world leading time of 1 minute, 56.72 seconds at the African junior championships in Bambous, Mauritius.
The test, which takes weeks to complete, requires a physical medical evaluation, and includes reports from a gynecologist, endocrinologist, psychologist, an internal medicine specialist and an expert on gender.
Semenya did not attend the news conference after winning Wednesday night's race by a margin of more than 2 seconds, in 1 minute, 55.45 seconds. She was replaced at the dais by IAAF general secretary Pierre Weiss.
Weiss said the testing was ordered because of "ambiguity, not because we believe she is cheating."
If the tests show that Semenya is not a woman, she would be stripped of her gold medal.
"But today there is no proof and the benefit of doubt must always be in favor of the athlete," Weiss said.
The most common cause of sexual ambiguity is congenital adrenal hyperplasia, an endocrine disorder where the adrenal glands produce abnormally high levels of hormones.
Gideon Sam, the president of South Africa's Olympic governing body, congratulated Semenya on a "truly remarkable achievement."
"We condemn the way she was linked with such media speculation and allegation, especially on a day she ran in the final of her first major world event," Sam said. "It's the biggest day of her life."
The medal ceremony for the 800 is later Thursday. Morris Gilbert, a media consultant for TuksSport, the University of Pretoria's sports department, said the issue of Semenya's gender has not been raised since the freshman began attending the school, where she studies sports science.
"We are all very proud of her and of what she's achieved," Gilbert said. "The university stands behind her all the way."
He attributed her recent success to hard work and rigorous training.
"She trains a lot," Gilbert said. "If you go to the athletics track, you're sure to find her there. I don't think she had really good training before she came to the university. She's from a very poor area."
Semenya's former school headmaster said he thought for years that the student was a boy.
"She was always rough and played with the boys. She liked soccer and she wore pants to school. She never wore a dress. It was only in Grade 11 that I realized she's a girl," Eric Modiba, head of the Nthema Secondary School, told the Beeld newspaper.
While Semenya's case has attracted a flurry of attention, it's not the first gender controversy in track and field history.
In 2006, the Asian Games 800 champion, Santhi Soundarajan of India, was stripped of her medal after failing a gender test. Perhaps the most famous case is that of Stella Walsh, also known as Stanislawa Walasiewicz, a Polish athlete who won gold in the 100 at the 1932 Olympics, who had ambiguous genitalia.
The IOC conducted the gender tests at the Olympics, but the controversial screenings were dropped before the 2000 Sydney Games. Among reasons for dropping the test, not all women have standard female chromosomes. In addition, there are cases of people who have ambiguous genitalia or other congenital conditions.
Associated Press Writer Anita Powell in Johannesburg contributed to this report.