DFA Most Wanted is a weekly spotlight on one specific Dillman family group with no representation yet in the Dillman DNA Project — who they were, what’s still unknown, and what a single Y-DNA test could resolve. Know this family, or think you might be connected? Read on.

Family Group 30: The Dielemans of Zeeland and East Flanders

This week’s spotlight isn’t just untested — it’s the single largest and oldest documented line in the entire DFA database, with no DNA representation at all. Family Group 30 traces back to Petrus Dieleman, born in 1450 in Wachtebeke, East Flanders, Belgium, and died there in 1533. Three generations later, a descendant named Francois Dieleman moved to the Netherlands, founding the family’s Dutch branch. From there, the family spread further still: 144 documented immigrating individuals, with recorded arrivals in the United States beginning in 1847, Canada in 1923, and Australia in 1951. Descendants live on at least three continents today.

What’s Unresolved

No single family group in the database has this much documented breadth — five and a half centuries, three continents, 144 individual immigrants — and none of it has ever been confirmed genetically. A Y-DNA test from anywhere in this vast family would be the first.

What a Test Could Answer

Given how large and geographically scattered this family is, a Y-DNA test could do more than confirm the paper trail — it could help determine whether every documented branch (Belgian, Dutch, American, Canadian, Australian) truly descends from the same Petrus Dieleman, or whether some branches, despite sharing the name, turn out to be unrelated. With 144 individuals to draw from, this family also has an unusually large pool of potential testers to reach.

Are You Connected?

If you’re a male-line descendant of Petrus Dieleman’s family — through the Belgian, Dutch, American, Canadian, or Australian branches — the DFA would very much like to hear from you. Contact the DNA project administrator at dnaprojectadmin@dillmanfamilyassociation.org to get connected and learn about testing.

This spotlight is drawn from the Dillman Family Association’s Family Group Sheet Database and written with the assistance of Claude, an AI assistant developed by Anthropic.