So why is the viral-spread aspect so cool? Well, from a starting point of a few dozen folks a few weeks ago, my Geni tree has grown to almost 400 people. Southerners, in addition to the more conservative forms of Protestant Christianity, tend to practice ancestor worship, so this is not unusual, but the Midwestern Jewish side of the family is more than holding its own.
The Geni system sends you updates when people are added to "your" tree, no matter how tenuous the links might be.
Some folks have gotten so enthusiastic about entering family members that there are now people I've not only never met, but never even knew existed, in our tree.
This system notification from Geni is the winner so far:
XXX just addded YYY, your first cousin's daughter-in-law's ex-husband's ex-wife.That right there is damn nearly a country and western song. Whew!