Blended Kinship & Consanguinity Pedigree Explorer

Five fictional diagrams with stored relationship values; no path calculation, genetic test or legal assessment

Stored Relationship (r)
0.0000
Stored cM Example / Expected r%
0 cM (0%)
Kinship Classification
Collateral Affinity
Hypothetical Offspring F Fixture
0.0000
Fictional Pedigree Diagram
Male
Female
Biological Union
Blended / Affinity Marriage

Diagram scope: Presets draw supplied nodes and lines. Values are stored independently; no ancestor traversal or relationship proof is computed.

Scenario Assumptions

Collateral Step-Siblings

No legal assessment
Scenarior fixturecM fixture
Step-siblings00
Half-siblings0.251750
Full siblings0.53500
First cousins0.125850
Double first cousins0.251750

What the Diagram Establishes

Stored values: r and F come from the selected fixture, not an equation evaluated from this diagram.
F scope: The fixture labels a hypothetical child of the highlighted pair. It is not either adult’s F or a probability of illness.
Context: Family roles and biological ancestry are different kinds of information. Step-sibling status alone cannot establish whether two real people have any shared ancestors.

A pedigree diagram is a family model, not a genetic test

What can a shared-ancestor diagram tell you, and what remains unknown?

The five choices load fixed diagrams and numbers. They illustrate different family connections, but changing the scenario does not run ancestor tracing, estimate DNA segments or check any law.

All people are fictional. Founder lineages are assumed unrelated with no inbreeding or additional shared ancestry. The diagrams omit some relatives, especially the grandparents behind the double-first-cousin example. cM values are stored examples with no measurements, distributions or conversion model; F is a hypothetical offspring fixture, not a clinical risk estimate.

Try a worked example

Select First Cousins: the stored r is 0.1250, the display shows 12.5%, cM is 850 and hypothetical offspring F is 0.0625. Select Half-Siblings: r is 0.2500, cM 1750 and F 0.1250. The cM difference is 900, but the page does not derive either cM value from r. In these fixtures F equals r/2; that relationship assumes a simple pedigree and should not be applied indiscriminately to real families.

Follow relationships before interpreting numbers

NHGRI describes a pedigree as a diagram of family relationships used to track inheritance. A line in this example records a supplied connection; it does not verify ancestry or a person’s diagnosis. NHGRI: pedigree

The NHS genomics glossary groups full siblings as first-degree relatives, half-siblings as second-degree and first cousins as third-degree. Their average sharing is approximately 50%, 25% and 12.5% respectively; recombination creates variation between individuals. These averages do not make a fixed centimorgan example a measured result. NHS genomics: first-degree relatives NHS genomics: second-degree relatives NHS genomics: third-degree relatives

Keep family roles and scope separate

Step relationships arise through family arrangements, rather than establishing biological descent. The r = 0 step-family fixture explicitly assumes no shared ancestry; the label step-sibling alone cannot prove that assumption for a real family.

Highlight colors identify the pair described by the fixture. Nodes have hover styling but no click-to-recalculate interaction. Selecting a preset replaces the diagram and stored metrics; Reset restores the step-family example. JSON preserves the fixture and scope; SVG preserves the selected illustration. Neither export establishes a legal right, a medical finding or an illness probability.

Sources and further reading
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