I have worked on my tree through Ancestry.com for many years to include furnishing my DNA.
My brother's daughter started a tree through Ancestry and gave her DNA also; the results shows her as my half niece with 1845 cm and 43 segments and it shows my brother as my half brother through our father. My brother didn't furnish and is not interested in furnishing his DNA.
Here is the kicker... there were stories about my grandfather having an incestuous relationship and a baby with his daughter, my father's sister.
Is it possible given the 1845 cM and 43 segments that my niece has with me, that my brother is a product of a relationship between my grandfather and his daughter, my aunt?
This has been a difficult question to ask!