# Ancestor question **URL:** \ **Category:** Factual Questions\ **Created:** [June 12, 2003, 4:59pm UTC](https://boards.straightdope.com/t/ancestor-question/181371 "2003-06-12T16:59:36Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![insider](https://avatars.discourse-cdn.com/v4/letter/i/bbe5ce/32.png) [@insider](https://boards.straightdope.com/u/insider)\ **Post date:** [June 12, 2003, 4:59pm UTC](https://boards.straightdope.com/t/ancestor-question/181371/1 "2003-06-12T16:59:36Z")
What numbers are we looking at if we go back 10-20-30 or more generations in an individuals family history? If I have that many ancestors and all several billion people on the earth have the same, how is it possible to have that many people on the earth? I guess that some generations have collapsed in on themselves by incest but it seems like there can not be enough ancestors for all the people today. I guess I am confused. ---
**Author:** ![AllShookDown](https://avatars.discourse-cdn.com/v4/letter/a/d9b06d/32.png) [@AllShookDown](https://boards.straightdope.com/u/AllShookDown)\ **Post date:** [June 12, 2003, 5:09pm UTC](https://boards.straightdope.com/t/ancestor-question/181371/2 "2003-06-12T17:09:28Z")
Once you go back so far you have a certain number of grandparents but they aren’t all _different people._ Here’s a [good explanation.](http://www.generations.on.ca/genealogy/pedigree.htm)