KABUL, Afghanistan — Khadija is 18 now, just a year older than the Afghan war itself, and she has already been married three times — to three brothers.

One was a Taliban insurgent, killed fighting the United States Marines. One was a policeman, killed fighting the Taliban. One was an interpreter for the Marines who is now hunted by the Taliban, who have threatened to kill him and his infant son.

The story of Khadija and the three brothers she married is an account of war and tradition that is tragically Afghan. It encompasses the bitter arc of the Afghan war in its most violent place, Helmand Province in the south, the Taliban stronghold where many families have been torn apart by loyalties divided between the government and the insurgents.

It is also the story of women in a traditional society struggling against the lack of choice their culture gives them in their own lives. Their Pashtun society considers it the duty of brothers to marry their brothers’ widows — and leaves those widows with little choice but to obey, or lose their children and their homes.