TEMPLATE
Adoption Pedigree
Adoption is shown with dashed descent lines and square brackets around the adopted person. A child adopted out of one family and into another appears in both families: dashed line from the birth parents and bracketed lines from the adoptive parents. This example shows both conventions in a single editable chart.
Inheritance pattern & biological mechanism
Adoption notation cleanly separates biological ancestry (the transmission path for genetic alleles and heritable health conditions) from social, legal, and environmental family rearing. Standard medical genetics conventions use square brackets and distinct line patterns to ensure that hereditary risks are evaluated through genetic parents while preserving accurate social pedigree records.
Key transmission rules
- Square brackets [ ] are placed around the individual symbol to denote an adopted person.
- Biological descent is represented by solid lines connecting the individual to their biological parents.
- Adoptive descent is represented by dashed lines connecting the individual to their adoptive parents.
- An individual adopted into a family has brackets with dashed lines pointing to adoptive parents [adopted-in].
- An individual adopted out of their biological family has brackets with a dashed line departing the biological union [adopted-out].
Representative real-world conditions
Unknown Family Medical History Evaluations
Adult adoptees seeking predictive genetic screening
Clinical pedigree documentation when biological parentage is unrecorded or partially documented through registries.
Carrier Screening in Adoptive Parents
Pre-adoption genetic counseling
Assessing biological risk when adopting children from communities with elevated founder mutation carrier frequencies.
Tracing Hereditary Cardiac Syndromes
Long QT syndrome, Hypertrophic cardiomyopathy (HCM)
Identifying biological relatives for cascade testing when an adopted individual presents with a cardiac arrhythmia.
How to analyze this chart
- 1
Generation I: Biological parents (I-1 and I-2) conceive child (II-1). Separately, adoptive parents (I-3 and I-4) establish a union.
- 2
Generation II: Child (II-1) is enclosed in brackets. A solid biological descent line traces back to birth parents (I-1 and I-2) marked as adopted-out.
- 3
A dashed adoptive line links the child to adoptive parents (I-3 and I-4) marked as adopted-in, alongside their biological child (II-2).
- 4
The chart cleanly documents that any hereditary condition in biological parents applies to child II-1, but not to sibling II-2.
Diagnostic checklist: confirming vs ruling out
Confirming clues
- ✓ Enclosure of the adopted individual inside square brackets.
- ✓ Clear distinction between solid (biological) and dashed (adoptive) connection lines.
- ✓ Maintenance of biological ties when tracing hereditary risks across generations.
Caveats & ruling out
- ⚠ Never draw adoptive descent with solid lines; doing so creates false assumptions of biological transmission in clinical risk algorithms.
- ⚠ Never calculate disease recurrence risks for adoptive siblings unless they share biological parentage.
Frequently asked questions
Why is adoption notation so rigorous in clinical genetics?
Confusing social parentage with biological parentage leads to incorrect genetic risk assessments, unnecessary invasive testing for non-biological relatives, or failure to perform cascade testing on at-risk biological kin.
How should an adoptee with unknown biological parents be drawn?
The individual is drawn in brackets with dashed lines to adoptive parents. Above them, biological parents are drawn as unknown symbols (diamond or dashed circles/squares) with question marks.
How do you represent foster care or guardianship on a pedigree?
Similar to adoption, foster care or non-legal guardianship is designated with dashed descent lines and annotated with descriptive notes beneath the symbol.