Mormonism says God impregnated Mary by sex

Mormonism teaches that God is made of flesh and bone, meaning God has a penis and is able to engage in sexual intercourse. Moreover, while it not articulated in any standard works, Mormon authorities have taught that Mary could be and was impregnated with Jesus through physical sex with God.

• Brigham Young (Mormonism's 2nd president-prophet): “The Father came down and begat him, the same as we do now…” [The Complete Discourses of Brigham Young, vol. 1, p. 321; February 16, 1849, Salt Lake City] (As citedhere by McKeever and Shafovaloff)
• Brigham Young (Mormonism's 2nd president-prophet): “The birth of the Saviour 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,” [Journal of Discourses vol. 8:27]
• Heber C. Kimball: “In relation to the way in which I look upon the works of God and his creatures, I will say that I was naturally begotten; so was my father, and also my Savior Jesus Christ. According to the Scriptures, he is the first begotten of his father in the flesh, and there was nothing unnatural about it.” [Journal of Discourses vol. 8:54]
• Joseph Fielding Smith (Mormonism's 10th president-prophet): “Jesus Christ is the only begotten Son of God in the flesh. Well, now for the benefit of the older ones, how are children begotten? I answer just as Jesus Christ was begotten of his father …Jesus is the only person who had our Heavenly Father as the father of his body” [Family Home Evening Manual (1972), 125, 126.]
• Orson Pratt: the Holy Ghost gave her[Mary] strength to abide in the presence of the Father without being consumed, but it was the personage of the Father who begat the body of Jesus; and for this reason Jesus is called 'the Only Begotten of the Father;' that is, the only one in this world whose fleshly body was begotten by the Father. There were millions of sons and daughters who he begat before the foundation of this world, but they were spirits, and not bodies of flesh and bones [The Seer, 158.]
• Bruce R. McConkie (LDS 'General Authority'): “…our Lord is the only Son of the Father in the flesh. Each of the words is to be understood literally. Only means only, begotten means begotten, and Son means son. Christ was begotten by an Immortal Father in He same way that mortal men are begotten by mortal fathers … There is no need to spiritualize away the plain meaning of the scriptures. There is nothing figurative or hidden or beyond comprehension in our Lord's coming into mortality.  He is the Son of God in the same sense and way that we are the sons of mortal fathers. It is just that simple” [Mormon Doctrine, 456-547, 466, 468.]

JOSEPH WAS ONLY MARY'S SECOND HUSBAND

• Orson Pratt: 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 together 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: … Inasmuch as God was the first husband to her, it may be that He only gave her to be the wife of Joseph while in the 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.[The Seer, 158.]
• Brigham Young (Mormonism's 2nd president-prophet): “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.” [Journal of Discourses, vol. 11:41]

JESUS WAS NOT BEGOTTEN OF THE HOLY GHOST

• Brigham Young (Mormonism's 2nd president-prophet): “Now Remember from this time forth, and forever, that Jesus Christ was not begotten by the Holy Ghost. … When the Virgin Mary conceived the Jesus, the Father had begotten him in his own likeness. He was not begotten by the Holy Ghost… What a learned idea' 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.” [Journal of Discourses, vol. 1:8]
• Joseph Fielding Smith (Mormonism's 10th president-prophet): “CHRIST NOT BEGOTTEN OF THE HOLY GHOST … Christ was begotten of God. He was not born without the aid of Man, and that Man was God! ... They tell us the Book of Mormon states that Jesus was begotten of the Holy Ghost. I challenge that statement.” [Doctrines of Salvation, Vol. 1:18]
• Joseph Fielding Smith (Mormonism's 10th president-prophet): “The birth of the Savior was a natural occurrence unattended with any degree of mysticism, and the Father God was the literal parent of Jesus in the flesh as well as in the spirit” [Religious Truths Defined, 44.]
• Ezra Taft Benson (Mormonism's 13th presiden-prophet): “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. Jesus was not the son of Joseph, nor was He begotten by the Holy Ghost” [The Teachings of Ezra Taft Benson, 7.]

GOD AND MARY ARE TOGETHER JESUS'S LITERAL BIOLOGICAL PARENTS

• “God the Father became the literal father of Jesus Christ. Jesus is the only person on earth to be born of a mortal mother and an immortal father.” [Gospel Principles (2009), 53]
• “[Jesus Christ] was able to make payment because he lived a sinless life and because he was actually, literally, biologically the Son of God in the flesh” [Messages for Exaltation: Eternal Insights from the Book of Mormon (Salt Lake City: Deseret Sunday School Union, 1967), 378-379.]
• “He is the Son of God, literally, actually, as men are the sons of mortal parents” [What the Mormons Think of Christ, 44.]

• Joseph Fielding Smith (Mormonism's 10th president-prophet): “Jesus was not the son of any mortal man. His biological father was God, the Father. As Son of God, Jesus represents the Father and acts as his agent in all things.” [The Restoration of All Things, 61.]
• James Talmage: “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.” [Articles of Faith, 466.]
• Melvin J. Ballard (Mormon apostle): “as to whether or not his was a virgin birth, a birth wherein divine power interceded. … And if God the Eternal Father is not the real Father of Jesus Christ, then are we in confusion; then is he not in reality the Son of God. But we declare that he is the Only Begotten of the Father in the flesh. … No man or woman can live in mortality and survive the presence of the Highest except by the sustaining power of the Holy Ghost. So it came upon her to prepare her for admittance into the divine presence, and the power of the Highest, who is the Father, was present, and overshadowed her, and the holy Child that was born of her was called the Son of God. Men who deny this, or who think that it degrades our Father, have no true conception of the sacredness of the most marvelous power with which God has endowed mortal men--the power of creation. Even though that power may be abused and may become a mere harp of pleasure to the wicked, nevertheless it is the most sacred and holy and divine function with which God has endowed man. Made holy, it is retained by the Father of us all, and in his exercise of that great and marvelous creative power and function, he did not debase himself, degrade himself, nor debauch his daughter. Thus Christ became the literal Son of a divine Father, and no one else was worthy to be his father.” [Deseret News, 23 Dec 1923; Sermons and Missionary Services of Melvin J. Ballard, 166-167.] (As cited,but in full, here by McKeever and Shafovaloff)