Rare set of semi-identical twins identified in Australia

A pair of Australian twins had researchers scratching their heads when it was discovered they were neither identical nor fraternal, but semi-identical siblings. In a new study published in The New England Journal of Medicine, scientists detail how they identified the set of semi-identical or sesquizygotic twins, only the second known pair in existence, during the mother’s pregnancy in 2014. At first, the fetal medicine team at the Royal Brisbane and Women’s Hospital believed the 28-y