ISTANBUL  Fethiye Cetin recalled the day her identity shattered.

She was a young law student when her beloved maternal grandmother, Seher, took her aside and told her a secret she had hidden for 60 years: that Seher was born a Christian Armenian with the name Heranus and had been saved from a death march by a Turkish officer, who snatched her from her mother’s arms in 1915 and raised her as Turkish and Muslim.

Ms. Cetin’s grandmother, whose parents later turned out to have escaped to New York, was just one of many Armenian children who were kidnapped and adopted by Turkish families during the Armenian genocide, the mass killing of more than a million Armenians by the Ottoman Turks between 1915 and 1918. These survivors were sometimes called “the leftovers of the sword.”

“I was in a state of shock for a long time  I suddenly saw the world through different eyes,” said Ms. Cetin, now 60. “I had grown up thinking of myself as a Turkish Muslim, not an Armenian. There had been nothing in the history books about the massacre of a people that had been erased from Turkey’s collective memory. Like my grandmother, many had buried their identity  and the horrors they had seen  deep inside of them.”

Now, however, Ms. Cetin, a prominent advocate for the estimated 50,000-member Armenian-Turkish community here and one of the country’s leading human rights lawyers, believes a seminal moment has arrived in which Turkey and Armenia can finally confront the ghosts of history and possibly even overcome one of the world’s most enduring and bitter rivalries.