The Twins

Once upon a time...
One evening in December 1987, Steeven was born, and fifteen minutes later, not wanting to leave his brother alone any longer, Christopher joined him.
Since then, the Twins have spent their time laughing. So they've made a living of it.
But as they passed their thirties, and a few grey hairs later, the brothers began to ask themselves existential questions.
What if their parents had confused them when they were born?
Are they a fascination of Mother Nature or just a genetic anomaly?
Are there enough schizophrenic twins to have a belotte?