Folbigg had been in jail since 2003, when she was sentenced to a 40-year jail term after being convicted of the murder of three of her children — Patrick, Sarah and Laura — and of the manslaughter of her first son, Caleb. Two years later the court reduced it to 30 years on appeal.

The infants had died between the ages of 19 days and 18 months. She was branded “Australia’s worst mother” by the media and convicted on the back of largely circumstantial evidence, including her diaries, which purportedly contained confessions of guilt, according to prosecutors at her trial.

She and her colleagues found that the children’s samples had a mutation in a gene called CALM2. Researchers now think that these mutations were caused by a specific interplay between the DNA of both parents, which would explain why Folbigg is a healthy individual, but her children were not. It’s impossible to fully understand the genetic interplay, however, because Folbigg’s ex-husband has refused to submit a sample for genetic analysis. The CALM2 gene contains the instructions for making a protein called calmodulin 2. Faulty calmodulin proteins had already been linked to an irregular heartbeat and other disorders. Vinuesa suggested that flawed calmodulin proteins caused the deaths of Folbigg’s