We have always been told that identical twins also have identical DNA. Now scientists from Eurofins, a genomic services company specializing in forensics and paternity testing, have found a difference in identical twins' DNA.
Eurofins sequenced DNA from sperm samples provided by two identical twins and a blood sample of the child of one twin. They found five mutations, known as Single Nucleotide Polymorphisms (SNPs), in the child and the father, but not in the twin uncle. This finding was confirmed using Sanger sequencing.
You can read the details in the journal Forensic Science International: Genetics at http://www.sciencedirect.com/science/article/pii/S1872497313002275.
Warning: The article is highly technical.