How to read and interpret your raw DNA data

What raw DNA data actually is

A consumer DNA test does not read your whole genome. The lab uses a genotyping chip that checks a few hundred thousand specific, well-studied positions in your DNA, called SNPs (single-nucleotide polymorphisms). Your raw data file is simply the list of those positions and the letters found at each one. So “analyzing” raw DNA data means looking up what is known about each position and reading your letters against it.

What is inside the file

The file is a plain-text table. Each row is one SNP, with an identifier (an rsID), the chromosome and position, and your genotype: two letters, one inherited from each parent. It looks like this:

# rsid       chromosome  position    genotype
rs4988235    2           136608646   AA
rs1815739    11          66328095    CT
rs53576      3           8804371     GG

Most files use genome build 37 (GRCh37) for the position numbers. The exact column layout differs slightly between providers, but every file comes down to the same thing: an rsID plus your two letters. You can read more about the references and builds we use on our methodology page.

How to read a single line

Take the first line, rs4988235. The rsID is a stable identifier you can look up in public databases such as dbSNP or SNPedia. This SNP sits near the LCT gene and relates to whether you keep digesting lactose as an adult. Your genotype (here AA) is what determines your result for it. In other words, reading raw DNA data is a repeated two-step: map each rsID to what research says about it, then read your own genotype against that. See a worked example on our adult lactose digestion page.

What you can learn from raw DNA data

The same file supports several kinds of interpretation:

• Everyday traits, from muscle fiber type to taste and earwax.
• How your body tends to respond to certain nutrients.
• Carrier status for some inherited conditions.
• Pharmacogenomics: how you may process certain medicines.
• Ancestry composition.

You can browse every marker we read, each explained and sourced, in the traits and health markers catalog. Each result is a likelihood drawn from published research, not a diagnosis.

What raw DNA data cannot tell you

Being honest about the limits matters. A genotyping chip reads only a fraction of the positions in your genome and misses most rare variants, so raw data is not a clinical or diagnostic test. Results are probabilistic: a marker that shifts the odds of a trait is not a verdict, and lifestyle and environment often matter far more than any single SNP. Nothing in a raw data file is medical advice. When something looks health-relevant, confirm it with a clinician and, where appropriate, a validated clinical test. We spell out how we handle this on our methodology page.

How to analyze your raw data

There are two practical routes:

• By hand. Look up each rsID on SNPedia, dbSNP, or the GWAS Catalog and read your genotype against it. Accurate, free, but slow and technical.
• With a report tool. Map thousands of positions to plain-English, sourced explanations at once. PossibleGenome does this from your existing file, shows the source behind each result, and never stores your raw DNA.

Download your raw data first

If you have not downloaded your file yet, follow the guide for your provider: 23andMe, AncestryDNA, or FamilyTreeDNA.

More guides

• What's inside your 23andMe or AncestryDNA raw data file
• How to analyze your raw DNA data (free and paid options)
• What your raw DNA data can and cannot tell you