I don't think biological lineage is directly related to the family-unit concept Benny. They're both important but the family-unit obviously might not involve biological parents, and it may vary over time too. I don't see this as a binary choice since both can be supported using distinct mechanisms.
 
Polygamy is not much different to extra-marital children as far as biological lineage goes - each child shares one parent but not the other.The main difference will be that there was probably a ceremony for a polygamous union. This then supports the view that union-type Events (e.g. marriage) are also separate concepts from 'lineage' and 'family-unit'. In other words, we cannot assume children result from married parents, and are subsequently raised by those same parents.
 
GEDCOM falls on the floor in a heap if presented with such cases, and this was a driving force for my own R&D project.
 
    Tony
----- Original Message -----
From: Benny Malengier
To: hvdb
Cc: gramps-users@lists.sourceforge.net
Sent: Friday, June 28, 2013 12:19 PM
Subject: Re: [Gramps-users] In the future there could be 3 parents ?




2013/6/28 hvdb <henke54@gmail.com>
that says that in the future there could be 3 parents instead of the 'usual' 2 ... isn't that something to think about how that in GRAMPS could be 'implemented' ?

It's easy to extend the family with more than two parents. But family in Gramps is about who raised children, not really about who provided DNA material. So in Gramps today, if there are 3 DNA providers, you make 3 families with 1 parent, all having the same child. If the child is then raised by still other people, you add a 4th family.

So, the family concept of two parents only breaks down if children are raised by a group, eg a commune, with no preference for the real biological parents. We encounter this in historic sources with polygamy/

We would loose compatibility with other software should Gramps alone adapt multi-parent families

These kind of things should only be solved when they arise.
There is a question already now to allow more than two gender, which is an issue already today: http://www.gramps-project.org/wiki/index.php?title=GEPS_027:_Gender_as_an_Entry_Field
That is not an issue with historical sources though. 

Benny

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