Scientists have been recording data in DNA for a while, but it has usually involved bacteria and other simple organisms. MIT, however, just took a big leap forward. Its researchers have used the CRISPR gene editing technique to record histories in human cell DNA for the first time. They've crafted a gene circuit that only expresses an enzyme when it's near a key immune cell molecule, building up mutations the more it's exposed to that molecule. All you have to do to extract "memories" is to sequence those genes. They'll tell you whether or not there was a lot of inflammation, for instance.
It's not limited to one input, either. The MIT team found that they could produce multiple RNA strands in response to specific conditions, such as the presence of a certain medicine.
You probably won't see this approach used in humans any time soon. Sorry, your medical history won't be written in your genes. However, it could be extremely helpful for studies. Scientists could better track the development of an animal from embryo to adulthood, and understand the advancement of cancer or infections. Think of this more as a stepping stone for other discoveries than anything else.