I picked up an article laying about, that described how
the first documented family burials occurred 4600 years
ago. they just found the grave sites. So the whole
family was buried together and the kids were facing
the parents.
The most interesting part is how they died:
"the group burials, which appear to have happened
together, tell a story of violent deaths. One skeleton
has an arrow tip lodged in one of its vertebrae.
Several of the skeletons have fractures that have
not healed, showing that they must have
happened shortly before death."
The possible cause?:
"patrilocal society, where families 'married out'
their daughters , either to avoid inbreeding or
build allegiances with neighbours"
[ that's still going on in traditional societies]
So, my guess is a vendetta between the two
sets of inlaws, or, if not, internal family feuds,
in the nuclear family. Either way, it must
have been ugly. They probably kept clubs
and arrows around the cave to defend
against burglars.
[the modern homicidal family unit- or at least self-destructive family]
Checkit: Guardian
World's oldest nuclear family unearthed In Germany
by James Randerson