There is no housemate on the show without secrets. Khosi is one of the most honest housemates on the show, yet it is expected that she has her secrets to keep. This is why as the show goes on, fans and housemates alike try to use personal information they just gained against their foes.
Family is a dynamic that fans like to explore. A single mother is always shamed, so most times this information would be kept hidden. This might have spurred the recent controversial debate and clarification.
Khosi has a mother-like relationship with a child. There have been assumptions by some fans that the child is hers. She had a discussion with housemates about the child and so many people still had questions about the birth mother of the child.

Her fans have come out to clarify the speculations. According to them, this is not the first time she has spoken about the child in question. The child is her niece.
The child scandal might have been a big blow to Khosi. Fans would have been upset at the hypocrisy if they found close to the end of the game that their fave who they thought was honest was hiding a child.