Don't know how I missed this.  The New York Times is carrying the first chapters of two (count 'em, two) new books about Siamese twin sisters.  Lori Lansens's "The Girls" is the more upfront and lucid of the two, explaining:

I have never looked into my sister's eyes. I have never bathed alone. I have never stood in the grass at night and raised my arms to a beguiling moon. I've never used an airplane bathroom.  Or worn a hat. Or been kissed like that. I've never driven a car. Or slept through the night. Never a private talk. Or solo walk. I've never climbed a tree. 

Shelley Jackson's "Half Life" strikes a more poetic (if a bit over-wrought) tone.  The setting of this first chapter is a parade for conjoined twins.  The "twofers" wear "brand-new T-shirts with rubbery silk-screened slogans, 'One's Company' and '22' and 'YESIAMESE,'" and "We-R-2-R-1-4-Ever," while a detractor stands by:

"Repent," advised the wizened lady in the plastic visor who protested every day at Market and Sixteenth. Today her hand-lettered sign read "GO BACK TO SIAM."

I don't know that there is a strong anti-conjoined twin presence in the U.S., but I guess that's why they call it fiction.