In the fall of 2007,while helping her ambitious older half-brother,Barack Obama,campaign for president,Maya Soetoro-Ng holed up in the basement of the Obamas Chicago home to pursue a long-held ambition: writing a childrens book. When Obama offered to introduce his little sister to his agent,Soetoro-Ng said she refused. And she did not show him her booka fictional paean to their mother,the free-spirited anthropologist Stanley Ann Dunhamuntil it sold to a publisher. Thats probably the stubbornness of a younger sister, she said. We all want to find our own path. When Soetoro-Ngs book,Ladder to the Moon,hit bookshelves,it added to a growing Obama family literary canon. Obama,whose first two books earned millions,recently published a childrens book. His wife,Michelle,just signed a contract with Crown Publishing for a book on the White House garden. The first ladys brother,the college basketball coach Craig Robinson,published a memoir last year. The presidents half-brother Mark Obama Ndesandjo,published a semi-autobiographical novel in 2009. Even the presidents mother has become a published author. In 2009,14 years after her death,Duke University Press published her 1992 doctoral thesis,Surviving Against the Odds: Village Industry in Indonesia. Now 40 and the mother of two young daughters,Soetoro-Ng has been mostly out of the public eye since her brothers election,living in Honolulu,where she teaches. Suddenly,she is making appearances on TV talk shows and a 10-city book tour. People are so curious about my brother and theyre curious about his family,and I cant really force my publicist to ignore that curiosity, she said. In recent years,wives of presidents and vice presidents have often written books while their husbands were in office. Hillary Rodham Clinton wrote several,including It Takes a Village. Barbara Bush gave readers a peek into White House life through the eyes of her springer spaniel,Millie. The difference with the Obamas,said the historian Doris Kearns Goodwin,is that the president was himself an accomplished writer before taking officeand his family members seem to have stories to tell. In this case,she said,youve got an extended family from different parts of the world and youve got a writing family with Obama. Soetoro-Ng said she had long wanted to write a childrens book. Becoming a parent,she said,forced her to confront the intense grief that came with knowing her mother and her daughter would never meet. She fixes that in Ladder to the Moon,a whimsical tale in which Suhaila travels to the moon to be scooped up in the arms of her wise Grandma Annie, who teaches her about suffering in the world. Soetoro-Ng,who says she wants to be judged on my own merits is already under contract with Candlewick to write a novel for young adults. My hope,she said,is that I can continue writing and in the future I can just be Maya Soetoro-Ng.SHERYL GAY STOLBERG