Clinical Pedigree Diagram
Male
Female
Biological Union
Blended / Affinity Marriage
💡 Path-Analysis Proof: Person 1 and Person 2 share zero biological ancestors. The link between their lineages is a marital affinity union between Parent A and Parent C.
Jurisdiction Legality Explorer
Collateral Step-Siblings
100% LegalCollateral step-siblings share no biological lineage (r = 0). Marriage is lawful in all 50 US states, UK, Canada, and Australia. Statutory affinity bans apply strictly to lineal ascendant/descendant step-relations (e.g. step-parent/step-child).
| Relation Type | Genetic (r) | Legality Status |
|---|---|---|
| Step-Siblings | 0% (0 cM) | Legal (50 US States) |
| Step-Parent / Step-Child | 0% (0 cM) | Banned in ~25 US States |
| Biological Half-Siblings | 25% (~1750 cM) | Prohibited (Incest) |
| First Cousins | 12.5% (~850 cM) | Legal in ~25 US States, UK |
Biological vs Legal Affinity Insights
Wright's Equation: $r = \sum (1/2)^L \cdot (1 + F_A) = 0$
Offspring Risk: Baseline population risk (~2-3%) for birth anomalies; no elevated homozygosity from consanguinity.
Context Note: Step-sibling marriages (such as Scarlet Vas & Tayo Ricci) often provoke public surprise because parents are married, but genetically and statutorily they constitute unrelated individuals.