When students in Stanford University’s Introduction to Bioengineering course sit for their final exams, the first question that they have to answer is about our ability to write DNA.

Scientists have fully sequenced the genomes of humans, trees, octopuses, bacteria, and thousands of other species. But it may soon become possible to not just read large genomes but also to write them—synthesizing them from scratch. “Imagine a music synthesizer with only four keys,” said Stanford professor Drew Endy to the audience at the Aspen Ideas Festival, which is co-hosted by the Aspen Institute and The Atlantic. Each represents one of the four building blocks of DNA—A, C, G, and T. Press the keys in sequence and you can print out whatever stretch of DNA you like.

In 2010, one group did this for a bacterium with an exceptionally tiny genome, crafting all million or so letters of its DNA and implanting it into a hollow cell. Another team is part-way through writing the more complex genome of baker’s yeast, with 12 million letters. The human genome is 300 times bigger, and as I reported last month, others are trying to build the technology that will allow them to create genomes of this size.

For now, that’s prohibitively expensive, but it won’t always be that way. In 2003, it cost 4 dollars to press one of the keys on Endy’s hypothetical synthesizer. This month, it costs just two cents—a 200-fold decrease in price in just 14 years. In the same time frame, the cost of tuition at Stanford has doubled, and is now around $50,000. Given all of that, the first question that Stanford’s budding bioengineers get is this:

At what point will the cost of printing DNA to create a human equal the cost of teaching a student in Stanford?

And the answer is: 19 years from today.