Speaking in generalities, genealogy in olden times was only done for those in positions o power. It was of great importance for instance, to trace the lineages of nobles, kings, queens, and emperors. Rulers wanted this information in order to prove that they had rightful claim to the ascension of power. This information also validated the person's qualifications for the position.
In order to claim the right to wealth and power, your ancestry had to prove that you were worthy of it. Proving this was no simple task and genealogy was the only means available in which to prove it.
One of the basic elemental truths about genealogy is that it can only be traced through truth. Documenting ancient ancestry can be difficult and many genealogies of the emperors and kings were fabrications, which did not actually prove anything.
Genealogy could also be a form of religious identity. In Biblical times, only descendants of a certain lineage could be Jewish priests. Thus, any candidate for Jewish priesthood had to be able to prove his lineage in order to be qualified to serve in the position.
Korean culture believes that that one's identity and social status was earned by the virtue and achievements of one's ancestors, and the need to have accurate descent records in order to maintain the integrity and efficacy of the ancestral rituals. So in a sense a Korean who did not know his lineage lacked any form of identity or worth in society.
In Portugal in the 16th to 18th centuries there was an obsessive fascination with genealogical literature. The Portuguese gave great attention to the "purity of blood," and where influence was vital and favors exchanged, it resulted in both conflict and extreme rapture. Alliances were sought that tended to increase the appearance of social esteem with the attainment of greater recognition and present the image of aristocracy.
So through the years genealogy has satisfied more than just idle curiosity. It has propelled people into positions of wealth, society, and power, becoming so important that integrity and honor was placed in jeopardy by the falsification of the data needed to prove the claims