Tatiana and Krista are lying on their backs, on a blue mesh bath seat designed just for them. Ordinarily, the twins hate being bathed and scream mightily, but today they lie back and make faces at their mother, Felicia Simms, who rubs shampoo on their skulls, which they happen to share.
The twins are joined at the head, just above the ear. The official name of their condition is craniopagus twins, and there isn't another set like these in the world.
If you look at them straight on, Tatiana is on the left, her gaze locked upward and to her right. Krista is on the right. Because they can't move their heads without getting into a pushing match, the girls have lively, darting eyes. They can't see each other's faces, although their mother has used mirrors to give them a glimpse.
Bathing, dressing and feeding them was at first a logistical challenge for Ms. Simms, 21, but now she's an expert. Krista chuckles when her mother squeezes a washcloth over them to rinse off the shampoo.
“You're enjoying your bath, aren't you?” Ms. Simms coos. “Maybe you'll be a party girl like your dad.”
Wednesday, Tatiana and Krista Hogan-Simms of Vernon, B.C., will turn six months old, which is a remarkable milestone. Most conjoined twins die within hours of birth, or are plagued with ailments caused by shared organs, vascular and circulatory systems.
But Tatiana and Krista are healthy and thriving. They smile and cry and jostle one another in their crib. Each week brings a fresh achievement. In late March, Tatiana surprised her mother when she grabbed her right foot with her fist, a feat still beyond the grasp of her chubbier sister.
But there are obvious reminders that these infants are different. Unable to roll, they spend nearly all their time on their backs, which has flattened the backs of their heads. Tatiana has even developed a bald spot, although she and her sister were born with a thick thatch of brown hair. Ms. Simms tried to breastfeed the twins but, because of their immobility, could manage only one girl at a time, sending the other into a fury. They rely on the bottle now.
And there are the endless questions about their future. Can they be safely separated? Should they be? If surgery is ruled out, what kind of life do they face? How will they learn to walk? Can they live independent lives if their skulls remained fused? And how will the family — an extended family that travels in packs, talks by cellphone constantly, eats most meals together but gets by on social assistance — cope with the conjoined twins over the long term?
These are questions Ms. Simms must confront as she prepares for another crucial medical test in Vancouver this Thursday. A cerebral angiogram is planned, in which blue dye is injected into the girls' blood to trace the shared blood vessels in their brains. Doctors hope this test will illuminate a bridge of tissue that connects the twins' brain stems. They want to know whether this bridge carries important brain signals between the two infants.
If indeed it transmits vital signals needed for vision, physical sensation or motor movement, then separation surgery could drastically impair or kill one or both of them. If it is simply tissue, surgery could get the green light.
But in the meantime the twins remain figures of curiosity, their parents at once celebrated and vilified. Strangers approach Ms. Simms on the street and at Wal-Mart, full of questions. In January, she and the girls and their grandparents were flown to Los Angeles to appear on The Tyra Banks Show.
