How genes shape human health

The instructions written in our DNA influence nearly everything about us, including which diseases we are prone to, and why.

Every cell in the body carries the same set of genetic instructions. How those instructions are read, and how they vary from person to person, helps shape not only how we look, but how healthy we are.

From DNA to trait

A gene is a stretch of DNA, but a gene alone does little; what matters is its expression, when, and how strongly, it is switched on. Variations in DNA influence that expression, and through it, observable traits, from hair colour to disease risk.¹

Small variants, large effects

Across the genome, individual differences in DNA sequence affect the expression of most genes.¹ Some of these variants sit not in the genes themselves but in the regulatory regions that control them, quietly tuning biology up or down. Mapping them has become one of the main ways researchers trace the genetic roots of disease.¹

Our genes do not dictate our health. But they shape the odds.

Why family history matters

It is also why family history is one of the strongest predictors of common disease. Cancer, cardiovascular disease, diabetes, and autoimmune and psychiatric conditions all tend to cluster in families, reflecting shared genes as well as shared environments.²

Why it matters

Reading the genome is increasingly how medicine understands the origins of disease, and in rare disease especially, where a single gene can hold the whole answer.