This is not a-typical. MySpace has been primarily women over 35 since 2005, and 11% of members there are senior citizens.
Who has the highest disposable income, most free time and greatest need to connect with family and friends at a distance? Particularly keeping uptodate with young members who don’t come to visit enough? Grandparents.
I know a few people who have connected their mothers (in their 70′s) to Twitter. It just takes time for the older generation to find out where the photos are being uploaded, lives being discussed, and they want in.
The number of US women over age 55 using Facebook grew by 175.3% since September 2008, making mature females one of the fastest growing demographic groups on the social network, according to usage statistics released by independent blog Inside Facebook.