Ayaan Hirsi Ali claimed that she lied about her peronal details (name and age) because she had reasons to fear retribution from her family and clan members.
The New York Times has seen some of the letters, one of which is from her sister warning: "almost all Osman Mahamud [her clan] in the region are on the look out for you. You are warned." In another letter from AHA's father the father said he didn't want to have any contact with her any more and writes: "Go to hell! And the devil is with you".
I don't have direct access to the NYT, but this is according to this report.