A now-deceased member of the Mac User Group developed a rather elegant genealogy app, initially for PPC Macs. His son kept it going for a few more years, the last version being officially supported by Mountain Lion.
I had all my family data that I accumulated, going back to a fellow born in 1791 in Ireland. This info was in Dropbox, the app installer on my main Storage ext HD.
I installed it on the 12-inch G4 PowerBook and imported the info and was pleased with the result. I must find out if the app works in El Capitan, it certainly fails the High Sierra test.