1. Security by Mike Shade
2. Whisper by Laura Harner
3. Baked Sean by Michael
4. Broken by Sage Whistler
5. Twin Temptation by Carol Lynne
There really are a lot of quite romantic and emotional stories on this topic of forbidden love, and I'm certain that I'll revisit this subject later. I purchased all of these books at Amazon or ARE, and believe they are still available from those venues.
On the same note, my own twincest books, Telling the Truth, Trapping Drake, and Setting the Trap, are all on sale the remainder of August for 40% off at my publisher's site, Breathless Press!