Like all three-year-olds, Susan Beatie is fascinated by animals. She wants to be a vet — maybe even a vet and a princess — when she grows up. At bedtime, she loves to climb onto her father’s knee and demand a story about a hungry caterpillar, a greedy bee or a snail sailing away on the tail of a whale. But the book she loves most is Mister Seahorse, which explains how male seahorses become ‘pregnant’. A quirky choice for a child, you might think, but entirely understandable given that this story has been used to explain to Susan the inexplicable: how she came to be. ‘It’s her favourite bedtime story,’ says her father Thomas, 38. ‘I tell her that’s what I did: I carried her in my tummy like Mr Seahorse, and she gets it. ‘She doesn’t think there is anything weird about it. There is a photograph of me pregnant, and she points to it all the time, saying: “Daddy, Daddy, I’m inside and I got bigger and bigger, and then I had to come out.