GENOMICS is the study of the whole genetic blueprint of living organisms, and it is turning out to be every bit as surprising and profound as space travel or splitting the atom. A tiny bacterium may have 160,000 base pairs, the chemical bits that make up the strands of DNA and RNA, while a human genome has 3 billion. The ability to map this information, known as genetic sequencing, has raced ahead with new technology, opening vistas on how genes function, how organisms compare with each other, how diseases take hold — and, perhaps, how they can be conquered.

The sequencing technology has also produced an avalanche of data. The genetic blueprint can be stored, compared, studied and transmitted as a digital file. In general, in the study of human genomes, it has been common practice for scientists to share sequencing data without the identity of the person from whom it came. But an important announcement from the National Institutes of Health has cast light on the need for more debate and clarity on a subject certain to challenge both science and individual privacy in the future.

The announcement concerns Henrietta Lacks, a poor black woman from Baltimore who was being treated in 1951 for cervical cancer at Johns Hopkins Hospital. At the time, doctors removed some of her tumor cells without her knowledge or consent. She died soon after at age 31, but the cells lived on — they showed a remarkable ability to grow endlessly in culture and became a bedrock of biomedical research around the world. However, as author Rebecca Skloot documented in her bestselling book, “The Immortal Life of Henrietta Lacks,” the descendants of Ms. Lacks did not know for many years that her cells had played such an important role in science.

In March, researchers in Germany published a scientific paper online that described the genome sequence of the HeLa cell line. The research could, at least in theory, expose possible disease risk among the Lacks family, yet once again its members had not been told or consulted. Six decades ago, when the original cells were taken from the tumor, there was no requirement for Ms. Lacks to give consent. But now that sequencing can expose an intimate genetic blueprint, does the family deserve some privacy or at least a role in deciding how the information will be used?

In a significant decision, Francis S. Collins, the NIH director, and Kathy L. Hudson, deputy director for science, outreach and policy, have announced an agreement with the Lacks family that the genome sequence will be used for research only under “controlled access,” in which researchers must agree to terms beforehand and two members of the family will sit on a panel reviewing proposals. The agreement is a smart first step, but the issue will grow only larger in the years ahead. Genetic data can be so revealing that it may not be possible to keep such information totally anonymous. A balance may have to be found between individual rights to privacy and the value of open, shared knowledge in advancing scientific discovery.