Modern methods are more rigorous, but still not without a few problems.
Kinship does not equal ancestry.
Are you talking about the difference between “family” and “biological lineage” (i.e. adoptions, step-parents, etc.)?
Yes that’s exactly it. Just because a man is your biological parent does not necessarily make him your father. Kinship is thicker than blood.
So I was thinking about this a little in the context of the book club discussion I had Wednesday about David Reich’s (and others) recent work as a “so what’s been happening since 2002?” update to Mapping Human History. With the explosion of DNA and protein sequence information coming out, I can envision a “flip-flop” in our understanding of ancient history from archeological information that is largely behavior and cultural (garbage heaps seem to be a common treasure trove) to genetic information that provides biological linkages. Hopefully it means we gain a richer view of the past and what it means to be human, but I do worry a little about losing the idea of kinship and the importance of non-biological relationships in history.