Twins joined at the liver, now separated - celebrate 18th birthday

In this October 1998 handout photo provided by the Copeland family, Caitlin and Emily Copeland are shown on their first day of school. Eighteen years ago, the twins were born joined at the liver and were separated at 10-months-old. (AP)

In this 1999 handout photo provided by the Copeland Family, Caitlin Copeland, right, squeezes her twin sister, Emily in Houston. (AP)

In this 2003 handout photo provided by the Copeland family, Emily, top and Caitlin Copeland sit on front steps in Houston. (AP)

In 1997 cover of H magazine provided by Children's Memorial Hermann Hospital, shows Dr. Kevin Lally holding Emily and Caitlin Copeland in Houston. Lally is the pediatric surgeon who performed the twins’ separation. They were born joined at the liver. On Tuesday, June 10, 2014, they celebrate their 18th birthday and graduate as co-valedictorians from a Houston high school. (AP)

In this June 5, 2014 photo provided by Children's Memorial Hermann Hospital, shows Dr. Kevin Lally, center, with Emily, left, and Caitlin Copeland, right, in Houston. Lally is the pediatric surgeon who performed the twins’ separation. They were born joined at the liver. On Tuesday, June 10, 2014, they celebrate their 18th birthday and graduate as co-valedictorians from a Houston high school. (AP)

In this June 5, 2014 photo provided by Children's Memorial Hermann Hospital, Dr. Kevin Lally, left, talks with Crystal Copeland. (AP)

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