Identical twins have the same genetic make up but they differ in development so are they in a way clones?
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Are identical twins clones?
A clone is an individual that is genetically identical to another (see wikipedia > cloning). As you said, identical twins (better called monozygotic twins) are genetically identical to one another and therefore an identical twin is a clone indeed.
The role of the environment
Be careful, to not think of clone (incl. monozygotic twin) as individuals that look exactly alike or behave exactly alike. Even for traits that are highly heritable, environmental variation is causing a lot of phenotypic variation and two monozygotic twins do not encounter the exact same environment and can eventually grow up to be very different people. Note that the two blastulas will differ a little bit in concentration of proteins, fats, developmental factors and other things. Such small differences can have important impact on the development of the fetus.
See this post on heritability to have a better understanding of the underlying environmental variation explaining phenotypic variation in populations.
But they are clone for life, right?
Well, it depends on the exact definition of clone but it is important to understand that the expression of genes varies a lot in response to the environment. See for example wikipedia > epigenetics. Also genes may change slightly as we age (see Can genes change as we age?).
Simple answer: No.
Merriam webster defines a clone as follows:
a plant or animal that is grown from one cell of its parent and that has exactly the same genes as its parent.
Identical twins have identical genes to their sibling not their parent. The reason behind this is that this definition of cloning refers to the artificial biotechnical method of creating genetically identical offspring. While identical twins are a naturally occurring phenomenon caused by a splitting of the embryo during early development.
Long answer: It depends entirely on how you define a clone.
On one hand there is the original (biological science) definition (used in Remi's answer) which is mostly applied to bacteria: In that definition, clones are distinct organisms with identical DNA information. In that definition, identical twins are indeed clones, since they share the same DNA information.
On the other hand there is the definition from Merriam Webser (quoted above) which is the nowadays more commonly used definition outside the scientific community (also depicted in popular movies like Star Wars). That definition refers to the technical process of "human cloning" which is defined in the The wikipedia article that Remi quoted:
Human cloning is the creation of a genetically identical copy of a human. The term is generally used to refer to artificial human cloning, which is the reproduction of human cells and tissues. It does not refer to the natural conception and delivery of identical twins.
According to that definition, identical twins clearly are not clones and they would probably be offended to be called such.