Now I am not sure if these kind of questions are allowed on this site but I found it interesting so here i go

A points to B and says " His grandfather adopted my grandfather " . Now what is relation between A and B.

There can be more then 1 answer. Actually it is real situation I got a complicated family.


The most straightforward relationship is

Father (B) and son (A).

The most reduced relationship is

A = B (self), with the two grandfathers coming from different paternal / maternal lineages - for example, if both grandfathers married the same woman at some point.

The weakest relationship is

A and B are more distantly related than through their grandfathers, if A’s grandfather sired A’s parent before A’s grandfather was adopted by B’s grandfather. If B’s grandfather disclaimed any prior progeny that A’s grandfather sired before adoption, there might not even be a legal relationship between A and B that originated from their grandfathers.

  • 1
    $\begingroup$ You got my upvote $\endgroup$ – Rishi Oct 13 at 15:20
  • $\begingroup$ Thanks @Rishi. What was the intended answer? (Feel free to wait until there have been enough answers posted first.) $\endgroup$ – Lawrence Oct 13 at 16:55
  • 1
    $\begingroup$ I think I am gonna accept your answer it is best I got yet . In real B is my >! Uncle $\endgroup$ – Rishi Oct 14 at 5:45
  • $\begingroup$ @Rishi Thank you! $\endgroup$ – Lawrence Oct 14 at 6:07

There is no genetic relation between A and B (the '?'). We have:

 A's GF
   |    \(adoption)
 A's F     B's GF
   |          |
   A        B's F
        \?    |

and according to http://genetic-genealogy.co.uk/supp/NonGenetictRelationships.html

Quantitative Measures and Coding of Non-genetic Family Relationships
By definition, the Coefficient of Relationship (R) between non-genetic family relatives is normally zero.

(right at the end of the page)

  • $\begingroup$ Yeah but legally is since adoption is a legal process . That is why I avoid writing blood relation . In real I am A and B is someone in my family . I call him something. $\endgroup$ – Rishi Oct 13 at 10:40
  • 1
    $\begingroup$ If you want a non-puzzle answer, try at law.stackexchange.com. Adoption could be considered only legally binding while the adopters are still alive, for example. $\endgroup$ – JMP Oct 13 at 10:47

A addresses B as:

"adopted half first cousin once removed"


you (A) are a level lower than B, and one parent of B and your mentioned grandfather became half siblings after adoptation because your grandfather and the parent of B share only one common parent instead of two. Still, half-sibling means a genetic relationship, so maybe "adopted-half" protologism(?) or simply the word "adopted" must be used here. :)

  • $\begingroup$ >!Do you mean B is cousin of A $\endgroup$ – Rishi Oct 13 at 11:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.