Identical twins not so identical after all, study shows
- Thought to have minimal genetic differences, twins who come from a single fertilised egg that splits into two have long been important research subjects
- But the study shows diverging mutations that have implications for studies on the effects of nature versus nurture
Genetic differences between identical twins can begin very early in embryonic development, according to a study published on Thursday that researchers said has implications for how these siblings help scientists tease out the effects of nature versus nurture.
Identical – or monozygotic – twins come from a single fertilised egg that splits in two.
They are important research subjects because they are thought to have minimal genetic differences. This means that when physical or behavioural differences emerge, environmental factors are presumed to be the likely cause.
But the new research, published in the journal Nature Genetics, suggests that the role of genetic factors in shaping these differences has been underestimated.
“The classic model has been to use identical twins to help you to separate the influence of genetics versus environment in analysis of diseases,” said Kari Stefansson, head of Iceland’s deCODE genetics, a subsidiary of US pharmaceutical firm Amgen.
“So if you take identical twins raised apart and one of them developed autism, the classic interpretation has been that that is caused by the environment.”