An SNP, or single nucleotide polymorphism, is a common one-letter DNA difference at a specific genomic position that can be used as one context signal in personalization.
What the term means
DNA is written as long sequences of nucleotides. An SNP is a position where a meaningful share of the population carries one nucleotide instead of another. The term describes variation, not disease by default, and most SNPs have no clear practical meaning for day-to-day supplement decisions.
Why SNPs show up in personalization
SNPs can help explain why two people with similar goals, logs, and routines might process the same input differently. In Unfair-style ranking, an SNP belongs beside personalization weight, medication context, diet pattern, labs, and observed response. It should not outrank those signals by itself.
What an SNP can and cannot say
An SNP can support a hypothesis about enzyme activity, transport, receptor binding, or nutrient handling. It cannot prove that a person will respond to a given stack, tolerate a compound, or need a specific ingredient. Treating one variant as a direct instruction creates the same failure mode as any overconfident recommendation ranking.
Common interpretation mistakes
The most common mistake is reading population association as personal certainty. A reported association may depend on ancestry, sex, age, environment, co-medication, measurement method, or the outcome being studied. Even a well-studied SNP can be weak when it is removed from those details.
How this appears in Unfair
Unfair can treat an SNP as optional metadata attached to a profile, not as an automatic override. The signal is useful only when it helps explain a pattern already visible in logs, safety context, or evidence tier review.
Safety note
Genetic data should not be used as a stand-alone reason to start, stop, or escalate any supplement. Medication-related variants, unusual symptoms, or major lab concerns belong in clinician or pharmacist review.