Twin cousins explain how they are also brothers

Identical twins, also known as monozygotic twins, form when a single fertilised egg splits into two and grows into two separate embryos. The twins are the same gender, have the same blood type and share physical traits such as eye colour, hair colour and facial features. Identical twins may or may not share a placenta and/or amniotic sac. This is where things get a little bit more complicated, but don’t worry – the general principles aren’t that difficult to understand.