1) To date, the ones I have received include:
* Johnny Depp (actor) - 8th cousin 1x removed - common ancestor of Jonas Prescott (1676-1750)
* Marilyn Monroe (actress) - 7th cousin 2x removed - common ancestor is Joseph White (1662-1757)
* Matt Damon (actor) - 9th cousin, common ancestor is Moses Cleaveland (124-1702)
* Britney Spears (musician) - 8th cousin 1x removed, common ancestor is Ruth Collins (1685-1715)
* Bill Clinton (President) - 8th cousin 2x removed, common ancestor is George Soule (1593-????)
* Laurie Desmarias (FB friend) - 7th cousin 2x removed, common ancestor is Nathaniel Wade (1708-1754)
* Paul McCartney (musician) - 9th cousin, common ancestor is Adam Mott (1623-1711)
* Jennifer Meadows (FB Friend) - 8th cousin, common ancestor is Josiah Wood (1687-1753)
* Cherie Clark (FB friend) - 8th cousin 1x removed, common ancestor is Elizabeth ???? (1673-????), wife of Samuel Ayers (1669-1740)
* Cindy Bonham-Miller (FB friend) - 8th cousin 1x removed, common ancestor is Mariah Smith (1664-1724)
* Amanda Jensen (FB friend) - 7th cousin 2x removed, common ancestor is Richard Cutter (1682-1756)
* Bill Gates (Business) - 8th cousin, common ancestor is Hannah Benjamin (1668-1752)
* Mary Walker Rieder (FB friend) - 9th cousin, common ancestor is Thomas Wheeler (1621-1704)
* Meghan Trainor (musician) - 9th cousin, common ancestor is Hannah Rice (1658-1747)
* Kurt Cobain (musician) - 7th cousin 3x removed, common ancestor is Marie Sanger (1670-????).
* Kristen Stewart (actress) - 8th cousin 2x removed, common ancestor is Hannah Benjamin (1668-1752)
* Walt Disney (entertainer) - 7th cousin 3x removed, common ancestor is Elizabeth Cooke (1611-1663). This one is interesting - I don't have Elizabeth Cooke in my Ancestry Member Tree. She apparently is the mother of George Lawrence (1637-1708).
2) All of this could be great fun IF the relationships are correct. I believe my lines back in time are accurate because I have records and sources, but I can't tell if the other person's lines are accurate because no sources are provided. There are no links to online family trees for the famous persons, or for the Facebook friends. My assumption is that my Facebook friends who are on my list have done substantial genealogist work and their lines are correct.
I have asked Ancestry on their Facebook group page about the source. One of the responses from a user showed this screen:
The message says, in part: "...please note that the results are based on user-provided family trees. Ancestry does not guarantee the accuracy of the possible connections. They are intended as a starting point for your own genealogical research."
3) On another Facebook thread, Crista Cowan of Ancestry.com said: "Ancestry researchers (professional genealogists on staff) have done research on hundreds of family trees of celebrities,"
So there may be Ancestry Member Trees that has these celebrities? If I were doing this, I would create one big AMT, with attached records and sources, that could be searched by anyone. Are there AMTs done by individual researchers (professional or hobbyist) with these famous persons in them? How does Ancestry.com make the judgment about whether any of the trees are correct? Consensus is really not the right word!
But - if professional researchers are doing the trees of these famous persons, then why are there so many obvious errors? I refer the reader to my blog post Fact-Checking My WJB Clinton Relationship - WRONG! (20 October 2016). Judy Russell looked at five of her "cousins" and found errors in all five lines.
Crista also commented on an obvious error: "That looks like a stitching error. Just click the thumbs down at the bottom of that screen and it will be put in a queue to review."
That suggests that there may be a feedback mechanism that would judge the famous person's lines. That's good to know - but you have to click the down thumb icon on the screen.
There may be other useful comments on the Ancestry Facebook group page or in other resources.