At Thanksgiving dinner, there's probably a good chance you'll end up sitting beside your uncle.



You love your uncle, but you could do without all those chain e-mails that he forwards to you, the ones that claim the government is forcing you to get rid of your light bulbs, that "Obamacare" is going to put a tax on home sales and that President Barack Obama fits the biblical description of the Antichrist. (Note to uncles: We're not really singling you out. Chain e-mails get forwarded by aunts, grandparents and plenty of other relatives.)



So PolitiFact has put together this handy guide to chain e-mails and other viral messages. Hide it under the green bean casserole and you can pull it out if your uncle brings up the chain e-mails.



You should start by telling tell him that the e-mails are nearly always wrong. PolitiFact has checked 131 claims from e-mails and rated more than three-fourths of them False or Pants of Fire. Only 4 percent of the claims have earned a True.



The e-mails, heavy on exclamation points and ALL-CAPITAL LETTERS, are typically sent by conservatives who dislike Obama. Lately, though, we have seen a new phenomenon on Facebook, where liberal supporters of the Occupy Wall Street movement have been spreading messages, some of which aren't accurate. (More about them in a moment.)



The chain e-mails fall into a few broad themes:



Obama is unpatriotic! E-mails have said Obama complained that the troops were whiners (Pants on Fire), that he refused to say the Pledge of Allegiance (False) and that he wants soldiers to take a loyalty oath to him rather than the Constitution (Pants on Fire).



Democrats have passed a secret tax! Some recent e-mails claim that because of "Obamacare," monthly Medicare premiums will more than double by 2014 (Pants on Fire) and that home sales will be taxed 3.8 percent (Pants on Fire) to pay for the new health care law. Another one in this genre says Obama's finance team is seeking a 1 percent tax on all financial transactions (Pants on Fire).



Perks of office. Another theme in the e-mails is that members of Congress get excessive perks. The e-mails say members of Congress get full retirement pay after one term (Pants on Fire) and that congressional staffers and members don't have to repay their student loans (Pants on Fire).



The government is coming for your guns/health data/light bulbs! Some of the conspiracy theories are truly wacky. During the health care debate, one claimed that under the public option for health care coverage, people would be implanted with data-storing microchips (Pants on Fire). A more recent e-mail claimed the government was mandating that everyone get rid of their existing light bulbs (Pants on Fire). Another e-mail said you must list your guns on your tax return (Pants on Fire).



We're not sociologists, so we don't speculate why conservatives have been spreading most of the chain e-mails -- or why liberals have recently adopted a similar technique on Facebook for messages supporting Occupy Wall Street.



This week, we checked a widely circulated Facebook post that said 1 percent of Americans are millionaires compared with 47 percent of House members and 56 percent of senators. We found the numbers were off, particularly for the share of Americans who are millionaires (actually 9 percent), so we rated it Half True.



Likewise, many people were posting a message that said Republicans in Congress have introduced dozens of bills on religion, marriage, abortion and gun control, but zero bills on job creation. We found that was ridiculously false because the blog post it was based on included bills from both parties and there was no category for job creation. We rated it Pants on Fire.



The Facebook messages and the chain e-mails have this in common: they are spread by people who are passionate about their political beliefs. That's not a new phenomenon, of course, but what's different today is that people can spread their passion so quickly, to so many people, through e-mails and Facebook. They impulsively forward the e-mails and postings without bothering to see if they are accurate.



So tell your uncle to stop passing along the false e-mails -- or to check PolitiFact first. But it would be great if he could just pass the mashed potatoes.