Sequencing every UK baby’s genome is often presented as a simple route to personalised medicine. My article argues that the real challenge is not the science but what happens to the vast files afterwards. If the NHS keeps every genome in expensive “always on” cloud storage, the ten-year bill could run to hundreds of millions of pounds and extra carbon emissions. I show that moving genomes into much cheaper, slower “cold” storage after initial screening would cut costs by about 90% while still allowing results to be recalled when needed, freeing money for staff and patient care. (By Dr Timothy Hearn, https://jmg.bmj.com/content/early/2025/12/15/jmg-2025-111181 )