"Two exciting elements of mortality, both God-given, are worthy of our consideration. The first is that we receive a body that is physical, tangible, one that has feelings and powers not yet enjoyed by a spirit. This body is to facilitate our progress toward becoming like our Heavenly Father. Keep in mind that this 'gift' was created in the EXACT LIKENESS OF HIM WHOSE CHILDREN WE ARE. The second element is that some powers given to us through our bodies are inherently of God, and ARE UNIQUE TO HIS ORDER OF LIFE. Our natural feelings concerning the power to 'reproduce after our own kind' are holy and desirable. All we have and are, so far as our natural state is concerned, is good, for it is of God.......The powers to reproduce, then, are good, and cannot be considered evil......."(Achieving a Celestial Marriage, p. 17).
Luke 1:35 says, speaking of Mary, "The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee; therefore also that holy thing which shall be born of thee shall be called the Son of God." Some Mormon leaders have interpreted this verse to mean that for Mary, a human, to be able to 'withstand the presence of God,' that the Holy Ghost had to come upon her: "The Holy Ghost is the messenger of the Father and the Son. Mortal beings could not endure the presence of the Father without the Spirit overshadowing them, and that was the mission of the Holy Ghost, but not to beget the Son of God, THAT WAS THE BUSINESS OF THE FATHER. Jesus Christ is the Only Begotten Son of God the Father in the flesh, and in holding to this doctrine President Brigham Young is in perfect accord with the teachings in the Bible." (Joseph Fielding Smith, Answers to Gospel Questions, vol. 5, p. 128).
Here is the statement of BY's that JFS supports: "When the Virgin Mary conceived the child Jesus, the Father had begotten him in his own likeness. He was not begotten by the Holy Ghost. And who is the Father? He is the first of the human family; and when he (Christ) took a tabernacle, it was begotten by his Father in Heaven, AFTER THE SAME MANNER as the tabernacles of Cain, Abel, and the rest of the sons and daughters of Adam and Eve. Jesus, our elder brother, was begotten in the flesh by the same character that was in the garden of Eden, and who is our Father in Heaven." (JoD 1:50-51, also "Answers", vol. 5, p. 121).
To illustrate more clearly that BY meant that Christ's conception was actual physical sex, here is another of his statements: "The birth of our Savior was as natural as are the births of our children; it was the result of NATURAL ACTION. He partook of FLESH AND BLOOD--was begotten of his father, as we were of our fathers." (JoD, vol. 8, p. 115).
Here are a few more quotes from the 1962 Gospel Doctrine Sunday School Lesson Manual "Gospel Living in the Home," p. 16-17: "Jesus Christ is the Son of Elohim both as spiritual and bodily OFFSPRING; that is to say, Elohim is LITERALLY the Father of the spirit of Jesus Christ and also of the BODY in which Jesus Christ performed his mission in the flesh..." (as quoted from 'The Articles of Faith' by James E. Talmage, p. 466).
"We are told in the scriptures that Jesus Christ is the only begotten son of God in the flesh....how are children begotten? I answer, just as Jesus was begotten of his Father. The Christian denominations believe that Christ was begotten not of God, but of the spirit that overshadowed his mother. THIS IS NONSENSE. Why will they not believe the Father when He says that Jesus Christ is His Only Begotten Son? Why will they try to EXPLAIN THIS TRUTH AWAY and make mystery of it?" (as quoted from Joseph F. Smith, 'Box Elder Times,' Sep. 22, 1914).
"When the time came that His first-born, the Saviour, should come into the world and take a tabernacle, the Father came himself and favored that Spirit with a tabernacle instead of letting any other man do it. The Saviour was begotten by the Father of His spirit, by the same being who is the Father of our spirits, AND THAT IS ALL THE ORGANIC DIFFERENCE BETWEEN JESUS CHRIST AND YOU AND ME." (as quoted from 'Discourses of Brigham Young," 1925 edition, p. 77).
"The Holy Ghost came upon Mary, her conception was under that influence, even of the spirit of life; our Father in Heaven was the Father of the Son of Mary....." (as quoted from Joseph Fielding Smith, 'Man: His Origin and Destiny), p. 345.)
To allay any repugnancy from members on the idea of God having actual physical relations with the human Mary, some leaders pitched the idea that Mary was one of God's polygamous "celestial wives":
"The fleshly body of Jesus required a Mother as well as a Father. Therefore, the Father and Mother of Jesus, according to the flesh, must have been associated in the capacity of husband and wife; hence the Virgin Mary must have been, for the time being, the lawful wife of God the Father: we use the term lawful wife, because it would be blasphemous in the highest degree to say that He overshadowed her or begat the Savior unlawfully........He had a lawful right to overshadow the Virgin Mary IN THE CAPACITY OF A HUSBAND, and beget a Son.......Whether God the Father gave Mary to Joseph for time only, or for time and eternity, we are not informed. It may be that He only gave her to be the wife of Joseph while in this mortal state, and that He intended after the resurrection to again take her as one of his own wives to raise up immortal spirits in eternity." Apostle Orson Pratt, "The Seer," Oct. 1853, p. 158).
Pratt's statement is supported by one from Brigham Young: "The man Joseph, the husband of Mary, did not, that we know of, have more than one wife, but Mary the wife of Joseph had another husband." (Deseret News, Oct. 10, 1866).
The same idea is repeated in "The Life and Teachings of Jesus", 1974, p. 29: "Joseph was a mortal soul in premortality to be blessed with the signal honor of coming to earth and acting as THE LEGAL GUARDIAN OF THE SON OF THE ETERNAL FATHER IN THE FLESH."
And another statement from this same 1974 lesson manual, distributed to tens of thousands of LDS Institute students: "She, (Mary), heavy with child, traveled all that distance on mule-back, guarded and protected as one about to give birth to A HALF-DEITY. No other man in the history of this world of ours has ever had such an ancestry--God the Father on the one hand and Mary the Virgin on the other."
I repeat a quote from Ezra Taft Benson from 1988, published while he was president of the LDS church: "The Church of Jesus Christ of Latter-Day Saints proclaims that Jesus Christ is the Son of God in THE MOST LITERAL SENSE. The body in which He performed His mission in the flesh was SIRED by that same Holy Being we worship as God, our Eternal Father." (Teachings of ET Benson, p. 6).
Someone wrote here on ARM that the idea of God having sex with Mary was 'repugnant', etc. When the entire scope of the theology is laid out, it should not be repugnant to Mormons at all, as it ties in completely with the doctrines of pre-existence, eternal marriage, deification, plural marriage, etc. With the abundance of consistent statements on the subject, from a plethora of LDS leaders over the years, it's difficult to dismiss the concept as mere 'speculation.' The quote from Harold B. Lee that someone furnished is the only one I have seen saying that Mormons should not 'speculate' about it. Lee did not deny the concept; he merely advised not to discuss it. And as I quote above, church-dispensed lesson manuals have taught the same idea since Lee's 1972 death.
True, none of these quotes say specifically that God and Mary had sex in clinical terms, but in my opinion, considering the quotes in totality, it's naive to deny the implication. It has only been a few decades since pregnancy was described with code terms such as 'expecting,' 'with child', or 'in a family way.' LDS leaders were clearly following the etiquette of their day by not using the actual term 'sexual intercourse'. Considering the volume of this consistent teaching, in my opinion, Mormons who do NOT agree with this teaching are the ones who are 'speculating.'