Students know the 'little pieces'--DNA is copied in creation of each cell; each parent passes half their genetic holdings to the child. But the implications are wonderful... and often neglected. Each of us is the result of 3+ billion years of unbroken reproductive success... And each of us still bears 'living fossils dating back to those times'--our genes
I see this as a series of deductions about origins and history, each adding a twist or layer of complexity. From the common origin of blue eyes, the muliple ancestry of lactose tolerance to our ability to deduce multiple origins of sickle cell in the face of all bearing the same mutation, to the mystery of why short-legged dogs for DISTANTLY related branches of the 'dog tree' bear identical, incredibly unlikely mutations.