Chelsea Clinton, 29, the daughter of former US president Bill Clinton and the secretary of state, Hillary Clinton, has become engaged to her boyfriend, the investment banker Marc Mezvinsky. The couple sent an email to friends on Friday announcing the news. They said they were looking at a wedding next summer. Mezvinsky is a son of a former Pennsylvania representative, Marjorie Margolies-Mezvinsky and a former Iowa representative, Ed Mezvinsky, longtime friends of the Clintons. Ed Mezvinsky was released from prison last year after pleading guilty in 2002 to charges of fraud.