Since it is St. Patrick's day, my wife got it in her head to do family research stuff (she will do this every few years, the last time around was years ago, and we used Family Tree Maker for Mac, which apparently no longer exists or was renamed).
I was a little bit surprised at how many Mac family tree apps there are.
Macgenealogy.org says there are ten right now:
# Genealogy Pro 2.0.4
# ohmiGene: 0.91.9
# PAWriter II: v49
# Family Ties/Familienbande
# MacFamilyTree 4.2.7
# SeeGEDCOMX: 0.8b4
# Heredis Mac X.2
# GEDitCOM: 3.71
# MacPAF Under Dev.
# Reunion: 8.0.6
The only ones I recognize are Reunion and Genealogy Pro (and I thought Genealogy Pro 1 sucked). I didn't think the Mac market was big enough to support that many

because everybody I know that does it uses Windows and I'm not sure there is even that much software for Windows.