The feeling of great shame, regret and/or sadness for a historical moment or something that happened in the past.

When you eat dirt for the first time and leave your family to build a shack in the woods

The outpouring of sympathy for past transgressions that most times don't have anything to do with current generations. Take example the idea that Christians are pressured into feeling sorrow or guilt for the Holy Crusades in the middle ages. Or another example is the actual celebration of "Black History Month", a reverse-racist idea that was brought on by Black Supremacists that wished to "get back" at the entire white American population for hundreds of years of oppression. By badgering the media with propaganda and moving speeches enabled racist blacks to attain "Black History Month" by using "Historical Guilt". Another example still is the actual foundation of the state of Israel, which was brought upon by pressure of Zionists that seeking sympathy from the horrors of the Holocaust. The United States as well as the rest of the International community owed nothing to the survivors as well as subsequent generations of Holocaust survivors, yet the "Historical Guilt" plagued them to open their checkbooks.