Genetically, yes. Identical twins have the same DNA as do clones. Twins
also grow in the same womb and are affected the same by the mother's
nutrition and environment. Clones developed in different wombs will have
different environments.
There is one theory, not tested as far as I know, that twins are not
identical genetically. This theory states that a minor mutation occurs
early in the division. The theory then postulates that the cells with
different DNA split apart and form seperate individuals because their DNA
don't recognize each other as the same body. I heard this theory years ago
and have had not heard of any followup with DNA tests to confirm it.
I am an identical twin. We shared the same placenta, and are mirror twins.
Mirror twins occur when the blastula has already started to differentiate
(and has a distinct left and right side) when it splits into two
individuals. Because of this, my brother is a mirror image with reverse
internal organs.
We were difficult to tell apart through high school, but now we look no
more similar than we do with our older brother. I tease him that I am the
experimental rat on a vegetarian diet and taking life-extension drugs. He
is the control rat on a normal diet. When we are older, we will compare to
see how my life-extension theories are working. I like to think I look
younger than my brother, but I am not an unbiased observer.
-- Harvey Newstrom <mailto: harv@gate.net> PGP 5.5 Fingerprint F746 7A20 EB7D 27BA 80A5 4473 D8E1 6A54 1EB0 56F7 PGP Public Key available from <http://pgpkeys.mit.edu:11371>