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Semi-identical twins
A pair of semi-identical twins
Mar 29th 2007
From The Economist print edition
MARMOSETS are not the only animals to produce unusual twins, it seems (see article). Most human twins are either identical (ie, sharing all their genes because they started as a single fertilised egg) or fraternal (coming from two eggs fertilised independently at the same time). However, Vivienne Souter and her colleagues at the Banner Good Samaritan Medical Centre in Phoenix, Arizona, have discovered a pair of human twins that are neither identical nor fraternal.…
