The scientific analysis of your average brony has hit it's third installment. As of a few days ago, the question page is opened and everyone is invited to input their specific brony tastes.
Head on over to this page to contribute. As is the trend for the last two sections, it digs deep, so answer truthfully and don't take things personally!
On top if this, the Daily Dot has written a bit more on it. Check their article out here!
(This one also covers clop, so just avoid page 11 if you aren't comfortable answering questions about it.)