"There are two brief passages in the Creation account we can use to
draw some conclusions about human genetic history.
“And the Lord God formed man out
of the dust of the ground, and breathed into his nostrils the breath of
life; and the man became a living being.” Gen 2:7
“And the Lord God caused a deep sleep to fall on Adam, and he slept; and he took one of his ribs, and closed up the flesh in its place. Then the rib which the Lord God had taken from the man he made into a woman, and He brought her to the man.” Gen 2:21–22
These simple statements have profound implications.
---They put a limit on the amount of diversity we should find in people
living today.
---The Bible clearly says the human race started out with two
people only.
Q: But how different were these two people?
A: There is an
intriguing possibility that Eve was a clone of Adam. 
The science of
cloning involves taking DNA from an organism and using it to manufacture
an almost perfect copy of the original.
*Here, God is taking a piece of
flesh, with cells, organelles, and, importantly, Adam’s DNA, and using
it to manufacture a woman.
Of course, she could not be a perfect clone,
because she was a girl! Q: But what if God had taken Adam’s genome and used
it to manufacture Eve?
A: All he would have had to do was to leave out
Adam’s Y chromosome and double his X chromosome and, voilá, instant
woman!
I do not know if Eve was genetically identical to Adam. The only
reason I bring this up is because we have two possibilities in our Biblical model of human genetic history: one original genome or two.
Your genome is like an encyclopedia (almost literally). And, like an
encyclopedia, the genome is broken down into volumes, called
chromosomes, but you have two copies of each volume (with the exception
of the X and Y chromosomes; women have two Xs but men have one X and one
Y).
Imagine comparing two duplicate volumes side by side and finding
that one word in a particular sentence is spelled differently in each
volume (perhaps “color” vs “colour”).
*Can you see that if Eve was a
clone of Adam, there would have been, at most, two possible variants at
any point in the genome?
*If Eve was not a clone, however, there would
have been, at most, four possible variants at any point in the genome
(because each of the original chromosomes came in four copies). This
still allows for a lot of diversity overall, but it restricts the
variation at any one spot to 2, 3, or 4 original readings.
Q: Does this fit the evidence?
A: Absolutely! Most variable places in the
genome come in two versions and these versions are spread out across the
world. There are some highly variable places that seem to contradict
this, but most of these are due to mutations that occurred in the
different subpopulations after Babel.
The ABO blood group is a textbook example of a gene with more than two versions. There are three main versions of the blood type gene (A, B, and O). However, many, but not all, people with type O blood carry something that looks very much like a mutant A (the mutation prevents the manufacturing of the type A trait on the outside of cells).
*So here is a
gene with more than two versions, but one of the main versions is
clearly a mutation. This is true for many other genes, although, as
usual, there are exceptions.
The important take home point is that
essentially all of the genetic variation among people today could have
been carried within two people, if you discount mutations that occurred
after our dispersion across the globe. This is a surprise to many." CMI