progenitor

A progenitor is a direct line ancestor; that is, a person from whom you descend such as a parent, grandparent, great-grandparent, etc. We typically think of a progenitor as someone from an earlier time period. The term may also refer to the first person in a line of descent, perhaps in reference to an immigrant ancestor.

A progenitor or direct line ancestor stands in contrast to a collateral line ancestor, someone who is related but not in your direct line such as an aunt, uncle, or cousin.