Twins can have different parents. How is that possible? A fertility expert explains

Westend61/Getty Images A Gold Coast woman has given birth to twins who aren’t genetically related to each other, after becoming pregnant with a surrogate couple’s embryo and her own biological baby at the same time. This has produced one of the rarest outcomes in reproductive medicine, the first in Australia and only the third reported worldwide. Queensland law forbids twins being separated. So the case, ruled on by the Children’s Court of Queensland, has forced the courts to confront a…