Serena Williams has a sister.
Serena Williams . She has won 14 Grand Slam doubles titles with her sister Venus , and the pair are unbeaten in Grand Slam doubles finals . Serena has also won four Olympic gold medals , one in women 's singles and three in women 's doubles -- an all-time record shared with her sister , Venus . The arrival of the Williams sisters has been credited with ushering in a new era of power and athleticism on the women 's professional tennis tour .