Biology is even more complex than we anticipate. These identical twins could reasonably be assumed to look the same but, as shown here, this is not necessarily the case. The boys are monozygous but easily distinguishable. The genotypes for 8 highly polymorphic di-, tri-, and tetra-nucleotide microsatellite repeat markers turned out to be identical (1:2700).
The Lancet 1999;353:562
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