Three recent and forthcoming books happen to feature Siamese twins. PW calls it a "twin-lit revival" featuring "tales of literally inseparable characters!" If you're interested...
Ludmila's Broken English by DBC PierreLudmila trudges out of the Caucasus in search of help for her starving family-and runs into Blair and Bunny, conjoined British twins who have just been separated. Only daring (and controversial) Booker Prize winner Pierre would risk a plot like this.
The Girls by Lori LansensBookish Rose sets out to write her autobiography, which is complicated by her being conjoined to beautiful twin sister Ruby.
Half Life by Shelley JacksonAn unhappy conjoined twin, Nora will do anything to rid herself forever of her attached sister, Blanche, heading for London in search of a mysterious doctor who promises to eliminate Blanche, but when she arrives, her past begins to surface in enigmatic and disturbing ways.