Since it was founded nearly two decades ago, 23andMe has grown into one of the largest biotechnology companies in the world. Millions of people have used its simple genetic testing service, which involves ordering a saliva test, spitting into a tube, and sending it back to the company for a detailed DNA analysis. But now the company is on the brink of bankruptcy. This has raised concerns about what will happen to the troves of genetic data it has in its possession. The company’s chief executive, Anne Wojcicki, has said she is committed to customer privacy and will “maintain our…