From: exxjxw.hannivoort@inter.nl.net   
      
   Ian Goddard  wrote on 22 Jan 2020 in   
   soc.genealogy.britain:   
      
   > On 22/01/20 14:23, knuttle wrote:   
   >> On 1/22/2020 5:34 AM, Evertjan. wrote:   
   >>> I have a family tree whereby a group of siblings have four lines of   
   >>> descent from the same couple.  For three of these there are 7   
   >>> generations and for the other there are 6 generations.  The 7   
   >>> generation descent would give 128 distinct genealogical roles at this   
   >>> level and the 6 generation descent would give 64.  In fact I find 10   
   >>> individuals filling 24 of these roles so there are 14 "missing"   
   >>> ancestors due to pedigree collapse.   
   >> You do not mention the sex of the member of each generation. If you   
   >> mean by missing that you can find no one of the family name to fill the   
   >> missing position, then it can easily be explained by the ratio of males   
   >> to females.   If there are several generations where mostly females   
   >> are born in our society the family surname is likely to disappear for   
   >> that generation.   
   >>   
   >> My grand father had two boys,  the boys had five boys.  Only two had   
   >> one boy each, and the third generation of two boys had no boys.  So   
   >> for that line the family surname disappears.   
   >   
   > I put "missing" in inverted commas.  They are the difference between the   
   > actual number of people as opposed to the number there would be if there   
   > was no pedigree collapse.  For example one couple appears 4 times; if   
   > they didn't there would be 3 other couples in that generation.  I count   
   > those 3 couples as 6 "missing" people.   
   >   
   > There were no step children involved so they're "missing" in couples.   
   > the number of "missing" males and females is balanced.  Not all lines   
   > have been resolved so it's not impossible that there was more collapse,   
   > in fact there were a pair of brides with the same surname.  For one of   
   > them I can't get back beyond her father and for the other the number of   
   > known baptisms is a bit sparse so it's possible they could be 1st or 2nd   
   > cousins.  However for the purpose of calculation I've assumed that all   
   > the collapse is known so my 1 in 8 is in fact at least 1 in 8.   
      
   There are two types of "missing"   
      
   1 having ancestors by multiple ancestorial pathways.   
     [this is the norm in an ecological niche]   
      
   2 having ancestors that are not known by documentation   
     or trusted oral tradition.   
      
      
   --   
   Evertjan.   
   The Netherlands.   
   (Please change the x'es to dots in my emailaddress)   
      
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