This information was taken from distribution of memberships in publicly listed Second Life groups, so measure your grain of salt appropriately.
The obvious tilt is toward daddy/girl play, since that dances around the edge of the "ageplay" definition in the first place (As Sadako Shikami argues on her blog). Mother/daughter I'm not quite sure what to say about outside of the usual "Wonder if both of them are guys" faux-lesbian leanings. I thought twincest would've been MUCH higher, well above hermaphroditic and even trans. Interesting.