Deesha Dyer, a former music and hip-hop culture writer, has been selected as President Obama’s new social secretary, overseeing the parties and public events held almost daily at the White House. Ms. Dyer, 37, who spent the past two years as the deputy social secretary, will fill the position to be vacated by Jeremy Bernard, the first man and the first openly gay person to serve in that role. By choosing Ms. Dyer, the White House is drawing from a group of people who have been working for the Obamas since early in the administration. She began in the White...