Can someone explain to me in simple terms what "pedigree collapse" is?
From DDP:
Hardin Co John Doe 2006 - DNA Doe Project Cases
In 2021, the Hardin County Coroner’s Office contacted the DNA Doe Project to request help identifying the man and a biological sample from his remains was sent to the lab for processing. After seven months of complex, specialized laboratory testing, volunteer investigative genetic genealogists began the work to identify the man by analyzing his genetic matches and building his family tree.
“We had some challenges in this case – a bit of pedigree collapse – but we had a great team that came together to overcome them.” said team leader Rhonda Kevorkian. “There were some good clues to follow that brought everything together in just the right way.”
“We had a male DNA match who was also a good sized X-match, and since two males can only match through the X-path on their maternal lines, this was a huge help in this case,” said team leader Tracie Boyle. “Once we had a candidate and could confirm that the X-path lined up, that helped solidify our findings.”