Conversation so far:
What is this about?
The ancestry and identity of Melungeons has been a highly controversial subject.
What do the others say?
Secondary sources disagree as to their ethnic, linguistic, cultural, and geographic origins and identity, as they are of mixed racial ancestry.
What could be be said?
They might accurately be described as a loose collection of families of diverse origins who migrated, settled near each other, and intermarried.
Who was this about?
mostly in Hancock and Hawkins counties in Tennessee, nearby areas of Kentucky, and in Lee County, Virginia.
What where the ancetors about?
Their ancestors can usually be traced back to colonial Virginia and the Carolinas.
What was the marriage about?
They were largely endogamous, marrying primarily within their community until about 1900.

Question: What did this cause?
Self-contained rewrite: What did endogamous Melungeon marriages cause?