Reference summary — not medical advice or a personal risk estimate.
Family history of cancer (first-degree relative)
Quick answer
Not IARC-classified — this is not a chemical or physical agent IARC rates. Recognized as a cancer risk factor based on observational evidence. Family history. Applies to people with a parent, sibling, or child who has had certain cancers.
Summary
Having a parent, sibling, or child diagnosed with certain cancers is associated with a higher personal risk of the same cancer, even without a known inherited gene mutation.
What's not established
A family history increases statistical risk but does not identify a specific cause, and most people with a family history of cancer do not carry a known inherited mutation. This entry does not establish your personal risk or replace an assessment by a genetic counselor.
Evidence sources
Every claim on this page traces back to one of these. Click through to read the primary document yourself.
Primary sources
NCI
NCI — The Genetics of Cancer
Last reviewed: October 2026
Official reference list
A government list some readers use alongside the primary evidence. Meyron is not affiliated with it. A chemical being listed does not by itself describe a risk from any particular product.
- California Prop 65 list
State of California's list of chemicals known to cause cancer or reproductive harm.