Dual Atree (binary Ahnentafel) chart for Cousins

When starting a conversation about sharing Genealogy information with a distant cousin, I often want to set a frame of reference for our genetic connection.

I could send a Deep Connections capture… But it is confusing that it stops at siblings without showing the common ancestors.

Currently, I prefer to copy our 2 Pedigree Gramplet data. Then prune those trees back to reveal the mutual connection… leaving the Spouse as well as the direct lines of descendants. (Because it is hard to navigate blended families without that.)

That’s a LOT of work. So if I need something quick, I might jump over to FamilySearch & capture a ‘View my Relationship’ screen.

But I’d really like something that clearly attractively illustrates simple binary Ahnentafel (aka Atree) in the Chart view. FamilySearch apparently has one like that too. (Although I’m not certain how to access it. Nor why there’s a weird jog in the top generation of the sample appended)

If it could show multiple Atrees simultaneously, that would be better. Particularly, if it was possible to show the branching of (multiple) cousin Atrees at a mutual common ancestor marriage.

Optionally, the ability to show diverging Atrees associated with Pedigree collapse would be helpful. (Charts of “I am my own cousin”.) So, for an Ancestor that has more than 1 Ahnentafel number for a particular descendant, chart each of those Ahnentafel paths side-by-side.

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I imagine you’re familiar with WikiTree’s Relationship Finder tool, which is not as graphical but seems like it would still be useful. Have you tried it, and if so, what do you consider to be its pros and cons?

Some interesting side information.

I regularly am given ‘hint’ information online with indistinct relationships to myself or a specific ancestor.


  • my ancestor is their 3rd great-grandfather
  • generic Atree description ( for Mary Norris Allerton, the 11th g-grandmother in the Atree illustration above, XMFFFFMFFMMMMM would be her Atree identifier. Her Ahnentafal number would be 12447.)
    I might have inverted the XFMMMMFMMFFFFF as XMFFFFMFFMMMMM… since I can never remember if the F stands for Female or Father while the M could be Male or Mother. (My preference is to use gender symbols to eliminate that ambiguity. X♀♂♂♂♂♀♂♂♀♀♀♀♀ ) However, I do know that any odd numbered Ahnentafel ancestor is always a Female.

It’d be lovely if we had a Chart that printed a worksheet with the Active Person & designated common Ancestor with blank boxes (as defined by the Atree or Ahnentafel descriptor) adjacent to my (Home Person) Atree chart to the designated common Ancestor.

Here’s what WikiTree generates for the same relationship as the ‘View my Relationship’ in FamilySearch. It is nice that the pasted data retains the hotlinks. But the indenting is dropped by most posting software. And even the indented original is less intuitive the FamilySearch chart.

The drawback to both the online systems is that you cannot put in Research Placeholders into the trees. In my system, I can add persons/relationships marked as ‘hypothetical’ to make the feature work. Then delete the relationship. I had to add 3 missing generations to the WikiTree database to reveal the relationship between cousins.

Brian and Robert are fifth cousins twice removed

Brian McCullough and Robert Gray are both descendants of Michael Butz.

  1. Brian is the son of Ruth Marguerite (Thompson) McCullough (1938-2016) [confident]

  2. Marguerite is the daughter of Ruth (Horn) Thompson [confident]

  3. Ruth is the daughter of William Melchior Horn (1882-1932) [confident]

  4. William is the son of Edward Traill Horn (1850-1915) [unknown confidence]

  5. Edward is the son of Mathilda Louisa (Heller) Hay Horn (1823-1903) [unknown confidence]

  6. Mathilda is the daughter of Susanna (Butz) Heller (1783-1853) [unknown confidence]

  7. Susanna is the daughter of Christian Butz (1756-1821) [unknown confidence]

  8. Christian is the son of Hans Michael Butz (1726-1779) [unknown confidence]
    This makes Michael the sixth great grandfather of Brian.

  9. Robert is the son of John William Gray (1890-1984) [unknown confidence]

  10. John is the son of Alice Floretta Rimer (1861-1924) [unknown confidence]

  11. Alice is the daughter of Christian Rimer (1812-1889) [unknown confidence]

  12. Christian is the son of Elizabeth (Hilliard) Rimer (1786-1845) [unknown confidence]

  13. Elizabeth is the daughter of Anna Cecilia (Butz) Rimer (abt.1767-abt.1820) [unknown confidence]

  14. Anna is the daughter of Hans Michael Butz (1726-1779) [unknown confidence]
    This makes Michael the fourth great grandfather of Robert.

I thought you had it right the first time (assuming Father and Mother for F and M), but anyway, it reminded me of something else. I’m sure that you most other readers here realize that the identifier is simply the number converted to base two, and the digits changed to F’s and M’s, but I also found that it can be useful to sort a list of ancestors by the left-justified base two value (or F/M string), padding on the right with either spaces or with a value higher than 1 (or M); the results are different but both sorts can be useful.

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From my other thread: “Is there a simple cousin relationship graph?”

Where is this RelativeFinder addon? I cannot find it either as an installed item or as an available item.

The chart type is found on RelativeFinder.org and is based on the FamilySearch common tree.

It’d be nice if there was something similar in Gramps or an add-on.

So that’s why it is in the Ideas section

Ah HA! That 'splains why I could not find it in Gramps. Thanks!

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