How are spirits born? I'm interested primarily in LDS doctrine, but I welcome the perspective of other sects as well, as I believe that all of Christianity shares the same roots. Please specify from what denomination your view is from in your answer.

In reference to the vision of Mosiah Hancock, how are spirits born or created? We know from the scriptures that: 


  4 ... Have ye not read, that he which
  made them at the beginning made them male and female, (Matthew 19:4; KJV)


and,


  11 Nevertheless neither is the man without the
  woman, neither the woman without the man, in the Lord.
  
  12 For as the woman is of the man, even so is the man also by the
  woman; but all things of God. (Corinthians 11:11-12; KJV)


There are more scriptures that reference how man and woman are twain without each other, and how united they are one flesh. 

We know it is impossible to be exalted without being married and sealed, so there is obvious significance to the sexes being reunited. 

Mosiah Hancock mentions in his vision that before the creation of Earth, all the children of God were arranged in pairs, a male with a female, and that each pair seemed to have been created mates. 

I'm looking for further knowledge and insight into this. Considering we are created in His LIKENESS and image, I'm left to assume that all spirits are born unto heavenly parents like children on earth are born unto mortal parents. But if that is so, then why are they born with spirit bodies, and not bodies of flesh and bone like unto their resurrected parents? Are all spirits born as male-female twins? Are they actually born, or are they created? If created then how are they created?



Update, Aug 12th 2014

I was reading this article: “In the Beginning”: A Latter-day Perspective, and stumbled onto this:


  “‘And I, God, blessed them [Man here is always in the plural. It was
  plural from the beginning.] and said unto them: Be fruitful, and
  multiply, and replenish the earth, and subdue it, and have dominion
  over [it].’ (Moses 2:27–28.)
  
  “And the scripture says,
  
  “‘And I, God, said unto mine Only Begotten, which was with me from the
  beginning: Let us make man [not a separate man, but a complete man,
  which is husband and wife] in our image, after our likeness; and it
  was so’ (Moses 2:26).


The part I found most interesting was, "The likeness of God is a complete man, being husband and wife." This seems to be inline with Mosiah Hancock's vision, and spirits being created mates.
First, we don't even know what a spirit is, really. Is is heavy? Is it strong? Is it colorful? Can two spirits give each other a high five?

The collective understanding of (LDS) scripture is essentially:


Everyone had/was a spirit from before they were born. (Jeremiah 1:5)
It has the form of a person.

  All spirit is matter, but it is more fine or pure, and can only be discerned by purer eyes
  
  Doctrine and Covenants 131:7



And that's it.

It's hard to even ask intelligent questions, let alone answer them, about something that is so little understood.



Joseph Smith talked about the creation of spirits in the King Folliet discourse:


  I have another subject to dwell upon, which is calculated to exalt man...It is associated with the subject of the resurrection of the dead — namely, the soul — the mind of man — the immortal spirit. Where did it come from? All learned men and doctors of divinity say that God created it in the beginning; but it is not so: the very idea lessens man in my estimation. I do not believe the doctrine; I know better. Hear it, all ye ends of the world; for God has told me so; and if you don’t believe me, it will not make the truth without effect...
  
  I am dwelling on the immortality of the spirit of man. Is it logical to say that the intelligence of spirits is immortal, and yet that it has a beginning? The intelligence of spirits had no beginning, neither will it have an end. That is good logic. That which has a beginning may have an end. 


One directional eternity doesn't make sense, at least to Joesph Smith. Anything that is fundamentally eternal is eternal in any direction.

And Doctrine and Convenants 93:29:


  Man was also in the beginning with God. Intelligence, or the light of truth, was not created or made, neither indeed can be.




Of course, God is said to be the Father of spirits (Hebrews 12:9, D&amp;C 76:24). How does that fit into the picture?

In the same sermon, Joseph Smith also said:


  You ask the learned doctors why they say the world was made out of nothing, and they will answer, "Doesn’t the Bible say he created the world?" And they infer, from the word create, that it must have been made out of nothing. Now, the word create came from the word baurau, which does not mean to create out of nothing; it means to organize; the same as a man would organize materials and build a ship. Hence we infer that God had materials to organize the world out of chaos—chaotic matter, which is element, and in which dwells all the glory. Element had an existence from the time He had. The pure principles of element are principles which can never be destroyed; they may be organized and re-organized, but not destroyed. They had no beginning and can have no end.


It is the same way with the "intelligence" or "spirit" mentioned. It is eternal (in both directions), and was organized by the Father and Creator. 

Now whether this is literally the Casper-like spirit normally thought of or something more principal elemental that was organized, or created, into a full fledged spirit we don't really know...because we don't really know what a spirit is.