Two’s company but is three a crowd when it comes to parenting? Last year, the first human baby was born using a technique that brings together DNA from three people. This revolutionary in vitro fertilisation method prevents babies from inheriting mutated genes and getting serious diseases. The nucleus from an egg with faulty mitochondria is transferred to a donor egg with healthy mitochondria before or after fertilisation. Some people may find the idea of a baby with three parents controversial.
But it already happens in the natural world. Magpie geese sometimes form lifelong family units that consist of three parents. The trio – comprising one male and two females – will build a nest together and all take turns to incubate their eggs. What great teamwork!