Pedigree collapse

[PLegoux]

Hi,

@Mattkmmr

@PLegoux

I’ve that couple (Pedigree collapse, implexe in french) which seems to me to be relevant to that report but I can’t find it in the report:

Your couple (green) is not double first cousin, since the parents are from three different families, while double cousins are only from two families and pedigree collapse is not checked in this report.

In that thread I was looking for Pedigree collapse but that report doesn’t do that. How I can find them in Gramps (massively, not by just selecting one person and running deep connections gramplet)? Does another report or gramplet do that?

Thanks

[GeorgeWilmes]

@PLegoux

Does another report or gramplet do that?

Yes, try the “Ancestor Fill” text report. Here is sample output:

Generation 1 Number of Ancestors found 2 Number of theoretical Ancestors 2 percent of Ancestors found 100.0000000000% Number of single Ancestors found 2 Pedigree Collapse 0.0000000000%

Generation 2 Number of Ancestors found 4 Number of theoretical Ancestors 4 percent of Ancestors found 100.0000000000% Number of single Ancestors found 4 Pedigree Collapse 0.0000000000%

Generation 3 Number of Ancestors found 8 Number of theoretical Ancestors 8 percent of Ancestors found 100.0000000000% Number of single Ancestors found 8 Pedigree Collapse 0.0000000000%

Generation 4 Number of Ancestors found 16 Number of theoretical Ancestors 16 percent of Ancestors found 100.0000000000% Number of single Ancestors found 16 Pedigree Collapse 0.0000000000%

Generation 5 Number of Ancestors found 26 Number of theoretical Ancestors 32 percent of Ancestors found 81.2500000000% Number of single Ancestors found 26 Pedigree Collapse 0.0000000000%

Generation 6 Number of Ancestors found 42 Number of theoretical Ancestors 64 percent of Ancestors found 65.6250000000% Number of single Ancestors found 42 Pedigree Collapse 0.0000000000%

Generation 7 Number of Ancestors found 39 Number of theoretical Ancestors 128 percent of Ancestors found 30.4687500000% Number of single Ancestors found 37 Pedigree Collapse 5.1282051282%

Generation 8 Number of Ancestors found 32 Number of theoretical Ancestors 256 percent of Ancestors found 12.5000000000% Number of single Ancestors found 29 Pedigree Collapse 9.3750000000%

Generation 9 Number of Ancestors found 20 Number of theoretical Ancestors 512 percent of Ancestors found 3.9062500000% Number of single Ancestors found 17 Pedigree Collapse 15.0000000000%

Generation 10 Number of Ancestors found 8 Number of theoretical Ancestors 1024 percent of Ancestors found 0.7812500000% Number of single Ancestors found 8 Pedigree Collapse 0.0000000000%

Total Number of Ancestors found 197 Total Number of single Ancestors found 181 Pedigree Collapse 8.1218274112%

[PLegoux]

Thank you George but that’s only statistics. I want to know who are the corresponding ancestors.

[DaveSch]

Try in the Person Filter editor

Ancestral filters >> Duplicate ancestors of <person>

[jcsaaver]

How to find “most repeated” ancestors?

Hello!

I am wondering if there is any tool in Gramps that would allow me to sort my ancestors by the number of different descent lines connecting them to me.

My family has lived in the same area for two to three hundreds years, so there has been much interbreeding, and “repeated ancestors” are common.

But I would like to know who are the most repeated ones.

Any ideas?

---

Gramps v 6.0.0
Ubuntu 24.04

[emyoulation]

The answers above list the amount of pedigree collapse at a particular generation and find the ancestors who are parts of the pedigree collapse.

However, it does not include the degree of collapse. So maybe the conversation can pick up again with that.

The proposed Contextual Family Tree by José Borges (José Luís Cabral de Moura Borges) suggests it would show pedigree collapse… but again does not indicate the degree of collapse.
In his Visualization Designs for Genealogy Facebook group, he suggests another graph design for visualizing inbreeding analysis:

[StoltHD]

Graphs like this, along with many others, can be easily visualized using popular network graph tools such as Gephi, Cytoscape, yEd, or Tulip.

Imagine how simple it would be, with a tool like this—a network graph in Gramps—to adjust a view or tweak an algorithm when exploring anything related to “relationships.” All it takes is just a few mouse clicks or keyboard shortcuts.

Now, picture combining that visualization with data, such as DNA information.

Network graphs are incredibly powerful tools!

[emyoulation]

From Reddit/r/gramps • 27 Mar 2025
Delicious_dystopia

Is there a way to fix this? And I don’t mean go back in time to teach them about condoms.

Re-posted with a bit more clarity.
How do you deal with quasi inbreeding in the family?
Marie and Catherine are sisters so, starting with their parent the lines, because they are the same, themselves.
Is there a better way to manage this or is this it?

Seems to be a theme going. Another person asking graphs that represent pedigree collapse without repetition.

However, their tree illustration was Earliest Ancestors at bottom rather than top. (Which felt unnatural.) So here is the data and a FTV export with a bit of markup to indicate the pedigree collapse.

CSV data import via Import Text addon gramplet

Person,Surname,Given,Suffix,Gender,Birth date,Death date,Note
[I000020],Bizet,Jeanne,,female,,,
[I000012],Calus,Marguerite,,female,,,
[I000017],Dalpe,Jean,,male,,,
[I000001],Dalpe,Jeanne,,female,29 Sep 1765,20 Jan 1754,"Home Person, common Ancestor"
[I000004],Deveau,Claude,,male,,,
[I000011],Deveau,Jean,,male,,,
[I000009],Deveau,Joseph,,male,,,
[I000010],Deveau dit Joicoeur,Joseph,,male,,,"Proband, https://www.reddit.com/r/gramps/comments/1jl878j/is_there_a_way_to_fix_this_and_i_dont_mean_go/#lightbox"
[I000014],Emery,Marie-Mac,,female,,,
[I000013],Hayet,Louis,,male,,,
[I000007],Hayet,Suzzanne,,female,,,
[I000019],Lorion,Mathurin,,male,,,
[I000018],Lorion,Renee,,female,,,
[I000005],Perrault,Jean,Sr,male,,,
[I000006],Perrault,Jean,Jr,male,,,
[I000015],Perrault,Nicholas,,male,,,
[I000008],Perrault,Suzzanne,,female,,,
[I000003],Quintin,Catherine,,female,8 Mar 1700,18 Sep 1762,
[I000000],Quintin,Jean,,male,about Jul 1715,29 Nov 1770,"common Ancestor"
[I000002],Quintin,Marie,,female,10 Feb 1695,9 Aug 1778,
[I000016],Raclos,Madeleine,,female,,,

Marriage,Husband,Wife
[F0000],[I000000],[I000001]
[F0001],[I000004],[I000003]
[F0002],[I000005],[I000002]
[F0003],[I000006],[I000007]
[F0004],[I000009],[I000008]
[F0005],[I000011],[I000012]
[F0006],[I000013],[I000014]
[F0007],[I000015],[I000016]
[F0008],[I000017],[I000018]
[F0009],[I000019],[I000020]

Family,Child
[F0000],[I000002]
[F0000],[I000003]
[F0001],[I000009]
[F0002],[I000006]
[F0003],[I000008]
[F0005],[I000004]
[F0006],[I000007]
[F0007],[I000005]
[F0009],[I000018]
[F0004],[I000010]
[F0008],[I000001]

[emyoulation]

The Consanguinity addon Gramplet illustrates the collapse somewhat.

[brianneogg]

It would be nice if the fix could translate into Ahnentafel reports. Having it just say “same as ‘such and such number’” is rather off-putting and having them constantly repeated can be quite confusing. I don’t know if there is a way for numbers to reflect the collapse, perhaps with an addition of letters (when more than one child is present in the tree they become a, b, etc)?

I recently did a tree with an INORDINATE amount of inbreeding. It was difficult to make the document look nice because I had to leave out repetitive pictures and stories so it didn’t just look like filler.

[pgerlier]

I don’t know if it is relevant to the present discussion. This is what I get with the usual family lines graph:

It does not tell how many pedigree collapses there are in the DB, nor their degree. Collapses are only revealed from graphs, i.e. if no graph is drawn, there is no hint about them.