Although they only account for around three in every thousand deliveries, monozygotic, or "identical" twins are fertile fodder for crime writers and cop shows. This isn't surprising considering that DNA fingerprint testing is not able to genetically differentiate between the good and evil twin. But now German-based company Eurofins MWG Operon says it has found a way to do just that.

Scientists from Eurofins, a genomic services company specializing in forensics and paternity testing, 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.

The scientists say this provides experimental evidence for the hypothesis that rare mutations will occur early after or before the twins originate with the splitting of the human blastocyst in two, and that these mutations will be carried on into somatic tissue and the germ line.

Eurofins, which is the first company to offer such a test, says it should prove useful in forensic and paternity cases involving monozygotic twins.

The team's study appears in the journal Forensic Science International: Genetics.

Source: Eurofins