E Nomine
You don't need scripture to know that if you believe that God created Adam and Eve and ONLY Adam and Eve then brother and sister had to marry. Generations of incest breed mental disorders and if God wanted them to populated the world I doubt He wanted his creation to be a race of retards
Herein lies your problem,(the Adam and Eve only to be more specific.)Adam and Eve were not the firstGenesis 1:26 "And God said, "Let Us make man in Our image, after Our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth."Genesis 1:27 "So God created man in His own image, in the image of God created He him; male and female created He them."Genesis 1:28 "And God blessed them, and God said unto them, "Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, ad over the fowl of the air, and over every living thing that moveth upon the earth."On the sixth day, "male and female created He them". God created all the races, however, in the creation of "Adam" we will see in the next chapter that God stated purpose for Adam, and His intent for the Adamic race are that they are "to till the ground." That means that they are to be farmers.Genesis 2:1 "Thus the heavens and the earth were finished, and all the host of them."This chapter begins after the completion of the heavens and the earth, when it is fit for habitation. The "hosts" are the masses of people of every race, created on the sixth day, and their offspring, as each race multiplied "after their kind". "Hosts" in the Hebrew text, is given as "tsaba", which shows a binding unity within each group or race, such as organizing for war. In the Strong's Hebrew dictionary it is # 6635, it comes from the root meaning "to assemble to perform". Each of these souls or people, having been created, now stood ready to pass through this earth age. Each soul having the free will to choose light, or darkness.Genesis 2:2 "And on the seventh day God ended His work which He had made; and He rested on the seventh day from all His work which He had made."When God rested on the seventh day, all forms of plant and animal life was in existence, and man was the last in the creative process of God. In ancient writings from the second century A.D., translated from [Sanhedrin viii, 7]; "Why was man created last? That the heretics might not say there was a companion with Him in the work, i.e., that man should not have claim to share with Him." The work was finished on the sixth day, and all activity of God's creative efforts stopped on the seventh day. God rested from all the work involving the universe.Genesis 2:3 "And God blessed the seventh day, and sanctified it: because that in it He had rested from all His work which God created and made."All the rejuvenation that took place was finished. Though the so-called "higher critics" say there is a change in authorship from the "P" to the "J" manuscripts, because we are using our commentary from Ezra and Nehemiah's "Massoretic text" manuscripts of Dr C. D. Ginsburg, there should be no conflict in the continuation of thought between the first and second chapters of Genesis. Both chapters come from the same source, and not separate authorships written years apart. Genesis 2:4 "These are the generations of the heavens and of the earth when they were created, in the day that the Lord God made the earth and the heavens,"Genesis 2:5 "And every plant of the field before it was in the earth, and every herb of the field before it grew: for the Lord God had not caused it to rain upon the earth, and there was not a man to till the ground."It is clearly understood that the fish, the fowl, all the wild animals of every kind are created, and living on earth. All races of mankind have also been created, and multiplying also, except the Adamic race. With all this life, God is stating that there still is "no man to till the ground"; to be a farmer. Genesis 2:6 "But there went up a mist from the earth, and watered the whole face of the ground."This "mist" is the morning dew that watered the earth. Genesis 2:7 "And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul."The word "formed" is used [molded as clay] to describe the making of Adam. When man was formed he became a living creature. In the Hebrew it is "eth-ha-adham", which refers to the particular person "Adam", (not a generic form for man). The "Ha-Adham" [Adam] is the man that Christ will come forth through. Matthew 1:1-17, and Luke 3:23-38 both give us our documentation that this is true and did come to pass. Paul states in I Corinthians 15:21-23 that sin came into the world by the first Adam, but by the second Adam [Christ} all shall be made alive. Christ is the first fruits [to come out of the grave to everlasting life], and then "they that are Christ's at His coming". There was death by the first Adam, and salvation by Christ Himself. Genesis 2:8 "(And the Lord God planted a garden eastward in Eden; and there He put the man whom He had formed."In this "Eden" which God had formed, He put "eth-ha adham" [not any man, but "the Adam"]. This is the man "Adam" formed from clay in Genesis 2:7, and not the "male and female" of the races of the sixth day creation of Genesis 1:27-28. Eden is a special place that God made, following the seventh day of rest, for a special man called Adam.
http://www.theseason.org/genesis/genesis.htm