"Aunty Lani is the birth mother of my cousin."
Translation:ʻO ʻAnakē Lani ka lūauʻi makuahine o koʻu hoa hānau.
Argh! This isn't specific to this particular exercise, but I'm NEVER going to get the o/a distinction right if Duolingo keeps forgiving my mistakes. It's especially frustrating to figure out whether someone's stepmother takes a different form of possession than a birth mother. Sheesh. Maybe a long tooltip on how alienable possession relates to family terminology?
Aloha e Artikyulet! Sorry for the confusion! There's a bug in the Duolingo system that we've been trying to get staff to correct, which allows "a" in place of "o" as a "single character typo", even though that is not the behavior we would like.
To clear things up a little: someone's relationship to an older familial generation (or generations) is generally o-class (this includes parents, uncles, aunts, grandparents, ancestors, etc.), so one would use "o" for both stepmother and birth mother. "O" is also generally used for people within the same familial generation as yourself (siblings, cousins). A person's relationship to younger familiar generations (children, nieces, nephews, grandchildren, etc.) is a-class, as are relationships with spouses and their siblings, and romantic partners in general.