Seed magazine has an article describing research that claims to have identified a correlation between ambidexterity and bi-sexuality. The article doesn't say so but it seems clear that the explanation of the linkage is that there must be a gene for 'Ability to handle multiple choices'.
Anybody with DNA so characterized will do well in the new 'identity metasystem', this because they will presumably deal better (e.g. faster log-in, less mental stress, etc) with the multiple online authentication options (e.g. SAML, Cardspace, OpenID, etc) than another without the gene. Consequently, we should see this gene favoured in those populations that see multiple SSO options because having it will engender a small but nevertheless significant Darwinian advantage relative to not having it.
Expect to see numbers of cross-dressing, ambidexterous individuals grow accordingly.