The gender of Twitter relationships

Although men and women follow a similar number of Twitter users, men have 15% more followers than women.
Men also have more reciprocated relationships, in which two users
follow each other. This "follower split" suggests that women are driven
less by followers than men, or have more stringent thresholds for
reciprocating relationships. This is intriguing, especially given that
females hold a slight majority on Twitter: we found that men comprise
45% of Twitter users, while women represent 55%. To get this figure, we
cross-referenced users' "real names" against a database of 40,000
strongly gendered names.

Even more interesting is who follows whom. We found that an average man is almost twice more likely to follow another man than a woman. Similarly,
an average woman is 25% more likely to follow a man than a woman.
Finally, an average man is 40% more likely to be followed by another
man than by a woman. These results cannot be explained by different
tweeting activity – both men and women tweet at the same rate.

I read that on Twitter from…a woman whose tweets I follow.  I don't know who she is or, for that matter, how I ended up following her.