Whether genetic testing makes sense for you is decided mostly by your family history. The guidelines that clinicians follow do not test everyone; they test people whose history fits recognised patterns, because that is where a result is most likely to change what happens next. This guide explains which patterns point toward testing, what a result would and would not tell you, and why the decision sits with a genetic counselor rather than with an app or a home DNA kit.
When is genetic testing more likely to be indicated?
Professional criteria from groups like the American College of Medical Genetics and the National Comprehensive Cancer Network point to the same family-history features. The more of these that fit, the more likely a counselor is to consider testing.
- Cancer at a young age in a close relative. A first-degree relative diagnosed well before the usual age for that cancer is one of the strongest signals.
- Several relatives with the same or related cancers. Breast and ovarian cancer, or colorectal and endometrial cancer, cluster within the same hereditary cancer syndromes. A pattern across relatives weighs more than any single case.
- A variant already identified in the family. If a relative has tested positive for a BRCA1 or BRCA2 variant, or for a Lynch syndrome variant, testing you for that exact variant is faster and more definite than starting from scratch.
- A rare or telling cancer. Some cancers, such as male breast cancer or ovarian cancer, carry enough hereditary signal on their own to prompt a testing conversation.
- Certain ancestries. A few inherited variants are more common in particular populations, which a counselor factors into the decision.
A history with none of these is usually not a reason to test, and a counselor may say so. That is a legitimate outcome of the conversation, not a failure of it.
How much does family history change the odds of carrying a variant?
Testing is targeted at family histories because that is where the carriers are. When a notable family history of cancer is taken into account, about 1 in 7 people were found to carry a clinically actionable genetic variant, versus about 1 in 47 at average risk — a sixfold difference. That is a population figure that explains why the criteria are written around family history. It is not a personal probability, and a counselor’s assessment, not an app, is what turns your specific history into advice.
What would a result actually tell you?
A genetic test answers a narrower question than people often expect, so it helps to know the outcomes before you decide.
| A result can | A result cannot |
|---|---|
| Confirm or rule out a specific known variant | Tell you whether you will definitely develop a condition |
| Explain a pattern of cancers already seen in the family | Cover every inherited risk; many conditions have no single testable variant |
| Guide earlier or more frequent screening if a variant is found | Replace the family history that decided testing was worthwhile in the first place |
| Inform relatives, who may carry the same variant | Diagnose a condition on its own |
Even a positive result describes a probability rather than a certainty, because most variants are not fully penetrant — carrying one raises risk without guaranteeing the condition. A counselor interprets what a given result means for you and for the relatives who share part of your history.
Can a result be used against you?
This is the question that stops many people from testing, and the answer has a real legal basis with real limits. In the United States, the Genetic Information Nondiscrimination Act (GINA) bars health insurers and most employers from using your genetic information or family medical history against you. The protection does not cover life, long-term-care, or disability insurance, and it does not apply to employers with fewer than fifteen employees. A counselor can walk through how this applies before you test. On RHR’s side, your own record stays encrypted under a key only you hold, which the security model explains in full.
How do you prepare to make the decision?
The decision is easier and faster when the family history is already written down.
- Build a three-generation history with ages at diagnosis. Record who had which condition and how old they were, structured as a three-generation pedigree.
- Identify who the concern started with. The relative who prompted the question, the proband, anchors how a counselor reads the family.
- Find any genetic test results already in the family. A known variant changes what testing you would even need.
- Take it to a genetic counselor. Ask whether your history meets the criteria for testing, and what a result would change. The decision is yours and the counselor’s together; the history is the raw material.
RHR organizes the family history as a pedigree and produces a summary you can hand to a counselor. The methodology page lists the guidelines the insights are checked against and is explicit about what RHR does not do: it does not diagnose, and it does not decide whether you should test.
Before you go
Genetic testing is indicated by patterns in your family history, not by curiosity or by an app’s say-so. Cancer at a young age, several affected relatives, a known variant in the family, and certain ancestries are the features that point toward it. Write the history down, take it to a genetic counselor, and let the result of that conversation, rather than a default, decide whether testing is worth doing.