Maya Soetoro-Ng, Obama's half sister, book out in April, pegged to their mother, Ann Dunham

WASHINGTON–Maya Soetoro-Ng, President Obama’s half sister, comes out with a book, “Ladder to the Moon,” next month, hitting D.C. and other cities on a tour to talk about the story she penned: her late mother, Ann Dunham, talks to a grandchild she never knew.

The Obama family–extended–is churning out books: Last week, (March 16,) First Lady Michelle Obama announced a deal for a book about her White House garden, due out in April, 2012. Her brother, Craig Robinson, wrote a memoir, “A Game of Character: A Family Journey from Chicago’s Southside to the Ivy League and Beyond” published last April.

Obama is Soetoro-Ng’s older brother; she was born to Dunham in Jakarta, Indonesia and grew up in Hawaii.