Because the LDS Church views the fall of Adam as a positive event (for without it procreation would not be possible), it has been careful to avoid calling this act a sin. Instead, it refers to the partaking of the tree of knowledge as a transgression. Tenth President Joseph Fielding Smith said, “The ‘fall’ of Adam and Eve was not a sin but an essential act upon which mortality depends” (Answers to Gospel Questions 5:15). Page 29 in the 2009 edition of the church manual Gospel Principles also tends to give this impression.
However, on page 116 of this same manual, the following insertion is made linking transgression with sin. “The Lord said, ‘If thou wilt turn unto me, and . . . repent of all thy transgressions [sins], and be baptized, even in water, in the name of mine Only Begotten Son, . . . Ye shall receive the gift of the Holy Ghost’ (Moses 6:52).”
Though the bracketed word “sin” is not found in Moses 6:52 (in the Pearl of Great Price), it appears in every edition of Gospel Principles, going clear back to the first edition in 1978.
Mormonism Research Ministry Update, April 2015