Mapping the 3 billion molecules of the human genetic code is a stunning, unprecedented breakthrough. We can expect a series of amazing health advances cascading from this remarkable achievement. We can also expect a number of missteps and mistakes. When antibiotics were first introduced in the 20th century, healthcare leapt forward. But in our exuberance we often misused these powerful medicines, which lead to problems such as increasing bacterial resistance. Still, I would never want to go back to the pre-antibiotic era. Neither would I want to return to the days before the human genome was mapped. But don’t be surprised if we stumble as we are learning to walk in this genetic era of medicine.