which is not possible for identical twins." Identical, or monozygotic, twins occur when a single egg, fertilised by a single sperm, divides and makes two babies. These twins will be the same sex ...

Monozygotic (MZ) twins have been widely used in studies of human disease, endophenotypes, gene expression and gene–environment interactions. MZ twins are generally assumed to be genetically ...

Twins provide an almost ideal natural experiment for studies of human heritability. Monozygotic twins are genetically identical, whereas dizygotic twins share on average 50% of their autosomal genes.

The research surveyed more than 1,500 parents of monozygotic and dizygotic twins aged 3 to 9. It found that when one twin was typically developing and the other had a developmental condition ...