Fanny Alger (Custer) was the 2nd Wife of Joseph Smith. She was only 16 – Married in Early 1833 (Joseph Smith, age 27). Fanny’s parents were neighbors of the Smiths, and Alger lived with Joseph Smith and his wife, Emma. Fanny stopped living with the Smiths as a result of Emma having discovered their relationship and was dismissed as their housekeeper.
Given the documentation regarding this relationship, educated Mormons conclude that Fanny Alger was Joseph Smith’s first plural wife, since the alternative is that he was a philanderer, and an adulterer.