By Daniel Burke, CNN Belief Blog Editor

(CNN) - The founder of the Mormon church, Joseph Smith, wed as many as 40 wives, including some who were already married and one as young as 14 years old, the church acknowledged in a surprising new essay.

Smith's marital history had been the subject of frequent historical debate, but until recently Mormon leaders had taken pains to present its founding prophet as happily married to one woman. Now, the church says, "careful estimates put the number between 30 and 40."

The church, officially called the Church of Jesus Christ of Latter-day Saints, disavowed plural marriage in 1890 under pressure from the U.S. government, which had imprisoned polygamists and seized their assets.