How do they define "family"? I tried to find that in the article, but didn't see it (and didn't read every word in order to discover it).
Colloquially, you might say two families are distinct if there are no marriages or blood ties between them. But if you go back far enough, are there any distinct families by that definition, especially within one country or region?
EDIT: Nevermind. I can see how, by limiting relationships to one advisor relationship for each person, there would be more distinct families (or in another language, disconnected graphs).
Advisor-Advisee relationships now. I'm a math PhD student, and I can trace my "mathematical family" back to each of Newton, Leibniz, and the physician mentioned in the article Sigismondo Polcastro. What I learn from looking at my family tree is that it's quite interconnected. The additional relationships come from students who claim more than one advisor (like almost all of Hardy and Littlewood's students, for instance) or students who got multiple PhDs and therefore have multiple advisors.
Colloquially, you might say two families are distinct if there are no marriages or blood ties between them. But if you go back far enough, are there any distinct families by that definition, especially within one country or region?
EDIT: Nevermind. I can see how, by limiting relationships to one advisor relationship for each person, there would be more distinct families (or in another language, disconnected graphs).