The Jewish myths were part of the tradition of the elders. They eventually found their way into the Talmudic writings. The genealogy issue was an issue of placing the Jews in a superior position to the Gentiles. It could also have been an attempt to discredit Jesus since He was not from the tribe of Levy. With regard to the study of genealogy today, however, the main problem would link to obsession.
Obsessions are unreasonable.
If our motive is to determine whether we come from royalty, then we have a pride problem. After all, we are all sinners saved by grace. As a hobby I don't believe that the study of genealogy is anymore harmful than any other hobby. The key is balance. Hope this helps.