Three days short of their first birthday, they have tiny baby teeth, a vocabulary that includes "mama" and "bye-bye" - and the milestone of their first unassisted steps not far in the future.
Christine and Loice Onziga, the conjoined twins separated in April during a 12-hour operation at the University of Maryland Medical Center, are developing into normal, healthy children and are preparing to return to their native Africa next week.
"I feel so excited to go back home with the two healthy girls and to meet with the rest of the family," Gordon Onziga, 29, said yesterday at an early birthday celebration at the hospital, attended by more than two dozen medical professionals who have worked with his daughters. "I thought that I was going to just dream about it."
When the twins arrived in Baltimore in February fused together, they sometimes cried and screamed when they were touched or shifted. Now independent of each other, they happily wave hello and goodbye, open their arms for hugs and stand and walk - albeit with help.
But it took hours and hours of physical therapy after the operation to get the sisters to do even the most seemingly basic things, such as turn their necks. A combined six pounds when delivered by Caesarean section, the two were attached from the breastbone to the navel, with their hearts, livers and diaphragms joined.
"What we realized was they didn't know how to move," said senior pediatric physical therapist Elizabeth Cross, who along with Dr. Cindy Howard will accompany the Onzigas to the county of Koboko in Uganda's Arua district. "A lot of what we were teaching them was completely foreign."
After the operation, which was provided free to the family by the University of Maryland Medical System, the girls slept in flexible plastic braces, lined on the inside with foam, to help straighten out the curves in their backs.
Starting in May, Cross worked with them five days a week in the hospital's fourth-floor therapy gym, at first for 20 or 30 minutes at a time because they tired easily.
She bounced them on big medicine balls, trying to get them to stretch their bodies and practice moving muscles.
"We would say, `Where is Mommy?' and they would turn their head[s]. We would say, `Where is Daddy?' and they would turn their head[s]," said Cross.
The girls progressed at different rates, but fairly quickly. By June, they were sitting up. By mid-July, they had made it onto their hands and knees. By the end of August, Christine was able to pull herself up to a standing position. Loice achieved the same milestone a few weeks later.
Developmentally, Christine is right on target, Cross said, with the skills of a 12- to 14-month-old. Loice is a little behind, with some "solid" 10- to 11-month-old skills, but she is expected to catch up.
Dr. Eric Strauch, a pediatric surgeon who directed the operation with Dr. Marcelo Cardarelli, has been comparing the girls' progress to that of his youngest daughter, who was born two months earlier.
"They're looking around, they're smiling, they're almost walking," he said of the twins. "They're doing a lot of the same things my daughter is doing. They're probably within the range of what's normal in this country. I consider them normal."
Loice is technically the "dominant" twin because her heart had been pumping blood into her sister's when they were joined. But Loice is smaller and not as strong (she weighs about 14 1/2 pounds to Christine's 17).
Howard, the pediatrician who first came across the girls' case during an exchange-program visit to a hospital in Kampala, said Loice still has two problems with her heart: one abnormal opening between the pulmonary artery and aorta and another in the wall between the heart's two upper chambers.
Doctors expect to repair the holes - neither of which is life-threatening - on Monday, the twins' first birthday.
The surgeons were able to avoid reconstructive heart surgery in the initial operation because each girls' heart could pump blood on its own.
Each of the girls, who were released from the hospital in June, has grown into her own little person.
Loice, dressed yesterday in a white sweater and purple-and-white striped dress, likes to play but doesn't talk too much, Gordon Onziga said. Christine, wearing all pink, is more outgoing.
"She likes to do a lot of exercise and smiles a lot and she wants to talk to everybody," her father said.
In the arms of her mother, Margret, 30, who speaks little English, Christine proved that true yesterday, smiling and giving high fives to anyone who would play along.
The parents have been staying at Ronald McDonald House since their arrival.
Some members of the girls' medical team have all but adopted the family as their own. Howard, who will stay in the Onzigas' village of Leiko for about five days, said she has never been so close to a patient or a family.
She took the Onzigas on vacation with her own family twice - to a lakeside cabin in North Carolina for the Fourth of July and to the Outer Banks last month.
Cross went with the Onzigas to the Baltimore Zoo, where Gordon pointed out the irony that his native homeland has so many freely roaming wild animals, but that he had to travel thousands of miles to actually see them.
By the time the family arrives back in Uganda after their long journey, Cross hopes the girls will have progressed a few steps more - literally.
"My goal is to have them both walk in holding their parents' hands," she said.