According to the text, Sibling rivalry is a competition

    Sibling rivalry is a competition between brothers and sisters. Which brother is smarter? Who gets good grades than the other? Sibling rivalry is not unusual in families. It is more unusual on the tennis court. The Williams sisters, Venus and Serena, are star tennis players. They often compete. Is it the easiest or the most difficult part of playing against your own sister? The sisters say the game is important – not the other player. Does their relationship make their game more interesting? Some people think the game is not as exciting when sisters play. I don’t agree. I think their games are more exciting. Venus and Serena are both better as most other players in the world – sisters or not.