Cousin marriage family tree template
In every other template, the family fans outward: each generation back has twice as many people as the one in front of it. A cousin marriage breaks that. When two cousins marry, their child descends from the same set of great-grandparents through both parents at once, and the tree stops being a tree — it loops.
Genealogists call this pedigree collapse, and it is the structure underneath almost every royal family tree, the Habsburgs most famously of all. It is also the structure that defeats most family tree software, because a chart that assumes every line branches outward has nowhere to put a line that comes back.
Cousin marriage family tree template
Nine people across three generations: one set of grandparents, their two children with the partners who married in, and two first cousins who marry and have a child.
Who it's for
- Royal, noble and dynastic trees, where cousin marriage is the norm rather than the exception.
- Families — historically very common, and still common in much of the world — where cousins married.
- Anyone whose tree has produced a loop and whose current software refuses to draw it.
How to fill it in
Start with the shared grandparents. They are the ancestors that both halves of the tree run back to.
Add their two children, and the partners who married in from outside the family.
Add one grandchild under each couple. These two are first cousins.
Marry the cousins to each other and give them a child. The line now folds back: that child's ancestry converges on one couple from both sides.
Check the relationship labels — the app resolves the double relationships that a loop produces rather than picking one and hiding the other.
Tips
This is the tree shape worth testing your data on. If a structure is going to break, it breaks here.
The strict layout is the clearest way to read a looped tree; the fluid graph view shows the loop more dramatically. Both are a click apart.
Frequently asked questions
When two people who share an ancestor have a child, that child has fewer distinct ancestors than the doubling rule predicts — the same person occupies two positions in the chart. The family line has folded back on itself.
European royal houses married within a small pool of eligible families for centuries, so cousin marriages accumulated. The Habsburgs are the extreme case, and their tree loops so heavily that some members have far fewer distinct ancestors than they should.
Yes. Relationships are computed from the structure, so when someone is both your cousin and your aunt by marriage, both facts survive rather than one overwriting the other.