Advances in IVF meant that the couple were able to fertilise an embryo each, and both were placed into the surrogate's womb. File pic.

They were born at the same time to the same mother, but these babies are far from typical twins.

Calder and Alexandra may have shared a womb but, thanks to modern fertility treatment, they are actually half-siblings with different fathers.

The babies were born to London couple Simon and Graeme Berney Edwards via a surrogate they met in Canada.

Advances in IVF meant that the couple were able to fertilise an embryo each, and both were placed into surrogate Meg Stone’s womb. They are still classed as twins, even though they have different biological fathers.

Simon, 43, said: ‘It really is amazing that Graeme and I have been able to father one of our twins each. Meg did an amazing job – and it meant that she was actually pregnant by two men at the same time. Graeme and I have always wanted to have a family, and now we have our lovely twins.’

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