I started to chart a simple family tree when I realized something  shocking.
If I use this formula, 1 generation=20 years, and If I start from
1964(my birth year) and go back 1000 years(50 generations) to the year
964,I have computed my grandparents plus my mom and dad and came up
with this huge number:
           9,007,199,254,740,990 

   that's:   9 ZILLION (if this is even a number)
             7 TRILLION
           199 BILLION
           254 MILLION
           740 THOUSAND
             9 HUNDRED and
            90
This has to be true, doesn't it? I multiplied each generation by 2 and
added previous total generations.
     EX:                      Me
                           M       D               2
         1964             MD       MD              4      6
         1944           MDMD       MDMD            8     14
         1924       MDMDMDMD       MDMDMDMD       16     30

I know that the blood line and genes have change over the many
generations but We would not exist if one of those zillions of
ancestors changed just one little thing in their life. For example, If
, lets say, if it poured rain on one day hundreds of years ago and a
grandfather couldn't work that day and had relations with his wife in
the afternoon instead of at night like always and they conceived a boy
that directly links to us, I wouldn't be if it didn't rain or they
conceived at that exact moment.
I'm not sure what answer I'm looking for, I guess maybe some feedback
or if I'm wrong, how and why I'm wrong and how do I find the answer.
This is just for personal use, I find it fascinating!

Dear ibjulie-ga;

Thank you for allowing me an opportunity to answer your interesting
question. The answer is YES...um, and NO.

You are correct. If old grandpa (many times over) hadn?t gotten frisky
that day that it rained back in 1681 and at that very moment cause
your grandmother (many times over) to conceive your next closer direct
ancestor, YOU would not be here. Amazing isn?t it?

Your figure might be a bit high but you?re on the right track (that?s
a ?quadrillion?, by the way, not a ?zillion?). At this point one?s
Family Tree becomes a FAMILY FOREST, doesn?t it? Hey, what a clever
name! Someone would make use of it.

Oops. Too late. Someone already has?

FAMILY FOREST
http://www.familyforest.com/resources.html

Wait! How can this be? There weren?t a quadrillion living people in
the ENTIRE WORLD 50 generations ago?or EVER for that matter!

That?s right. Some of your ancestors are counted twice, ten times or
even hundreds of times because over the years all of our generational
and ancestral lines cross and re-cross many times. I think this
article will give you a better understanding:

[excerpt]
We all are blessed with two parents, four grandparents, eight great
grandparents and so on. If the average generation is twenty-five
years, in 1200 years (back to 800 AD, the time of Charlemagne) each
person has 281.5 trillion grandparents. That's the way geometric
progressions work. The number of grandparents doubles every 25 years
and in 12OO years or 48 generations, 281.5 trillion names would be on
your pedigree.

GENEALOGY PEDIGREE COLLAPSE
http://www.generations.on.ca/genealogy/pedigree.htm

This one also sheds some significant light on the subject:

50 generations = 2 quadrillion+ ancestors
40 generations = 2 trillion+ ancestors
30 generations = 2 billion+ ancestors
20 generations = 2,097,150 ancestors
10 generations = 2,046 ancestors
8 generations = 510 ancestors
7 generations = 254 ancestors
6 generations = 126 ancestors
5 generations = 62 ancestors
4 generations = 30 ancestors
3 generations = 14 ancestors = your 8 great grandparents, plus 6 from below
2 generations = 6 ancestors = your parents plus both sets of grandparents
1 generations = 2 ancestors = your parents

THE ODDS OF BEING RELATED
http://www.electroauthor.com/marcotte_genealogy/math.htm


Here?s the math (not that I understand it). Others have expressed an
interest in this issue besides you so some brainiac has apparently
already figured it out. The trick is to figure out what he?s talking
about. You seem to be something of a mathematician so you will
undoubtedly have better luck with it than I am willing to attempt:

A SIMPLE WAY TO COUNT PARENTAL LINEAGE 
http://home.gwi.net/antiques/mingus/howmany.html

So...

"Is the generational number of ancestors really mathematically this high?"

Theoretically, YES

"Do you REALLY have a "zillion" genetic direct ancestors?" 

NO, and no mathematical model that I know of can tell you how many you
really do have on calculations alone but suffice it to say that it is
far, far less than the quadrillion plus ancestors that most models
compute and produce.

See if you can make sense of the math and work it out yourself. Do
yourself a favor - Try not to dwell on it too much, oh, and have some
aspirin handy.


Below you will find that I have carefully defined my search strategy
for you in the event that you need to search for more information. By
following the same type of searches that I did you may be able to
enhance the research I have provided even further. I hope you find
that my research exceeds your expectations. If you have any questions
about my research please post a clarification request prior to rating
the answer. Otherwise, I welcome your rating and your final comments
and I look forward to working with you again in the near future. Thank
you for bringing your question to us.

Best regards;
Tutuzdad ? Google Answers Researcher


OTHER INFORMATION SOURCES

KINGS, KIN AND SCOUDRELS
http://www.tbgen.com/trammell/tra10.html

ONE HUNDRED INTERESTING MATHEMATICAL PROBLEMS, PUZZLES, DIVERSIONS,
AND AMUSEMENTS: NUMBER 21: ANCESTORS
http://www.j-bradford-delong.net/movable_type/2003_archives/002852.html


SEARCH STRATEGY


SEARCH ENGINES USED:

Google ://www.google.com




SEARCH TERMS USED:


"NUMBER OF GRANDPARENTS" GENERATIONS

GRANDPARENTS CALCULATE GENERATIONS

NUMBER OF PARENTAL RELATIONS

CALCULATE "HOW MANY ANCESTORS"

---

Request for Answer Clarification by ibjulie-ga on 31 Jul 2004 21:25 PDT

I looked at the following web site
http://home.gwi.net/antiques/mingus/howmany.html - A SIMPLE WAY TO
COUNT PARENTAL LINEAGE
I'm confused. at 7 generations it says we have 128 grandparents but
wouldn't you add all the previous grandparents for a grand total?

---

Clarification of Answer by tutuzdad-ga on 01 Aug 2004 07:18 PDT

Good question. The webmaster who posted this formula is Julian Mingus.
You might contact him to get a better insight into his mathematical
forumla and what the results actually mean.

MINGUS FAMILY WEB
http://home.gwi.net/antiques/mingus/

Regards;
tutuzdad-ga

Thank-you so much for you clear answers and prompt response

Most of us are the direct decendent of about a billion ancestors
(great,great, great,grandparents ect) and most of us are distant
cousins of several billion current inhabitants of this planet. If you
could draw a correct family tree, you would see that many of the lines
merge frequently after ten generatons, much sooner if a recent
ancestor commited incest. Even larger numbers occur if you assume we
can look back farther than about 4700 BC.   Neil