I've never seen these done as quilts, but I'm also a genealogist, and I believe the kind of "tree" she's talking about is like this:
http://www.stylscript.com/closeup.ph...es&piece=btree
You might also be inspired by this:
http://www.hollymonroe.com/portfolio...aebeltree2.jpg
or:
http://www.melickgenealogists.com/im...-fan-chart.jpg