There is a very good article on this subject with a lot more detail on Dick Eastman's Online Genealogy Newsletter. Click on his name to see it.
Do you have a family crest or coat of arms hanging in your home? Did you know that the likelihood of it being legitimate is almost zero? The truth is they do not belong to a family or surname.
Long ago a coat of arms was actually a knight’s armour and shield. They were also displayed on the flags and horses. The crest was the plume at the top of the knight’s helmet. This was so that he was identifiable on the battlefield.
These identifiable items were granted only to those who earned them and belonged only to a single man. He could pass this to his male direct line descendants. When the sons in each generation would inherit the paternal shield they would alter it slightly. This is called Cadency. When the father dies the paternal shield would be changed back to the original by the eldest son keeping the original in “play”.
When couples married they would merge their coats of arms. This is called Marshalling. You see this in coats of arms that have the arms side by side, one centered over another or perhaps divided into 4 quadrants.
Women could inherit the coat of arms from their fathers but they couldn't pass them on to their children unless they had no brothers.
The thing to remember is that the coat of arms or crests that you see for sale in the malls or online are completely phony and have no connection to your family tree. Don’t waste your money.
Update: March 7, 2009 There are some exceptions, again very few, that come out of Eastern Europe etc.