Atlanta — At the Scott residence in Sandy Springs, Ga., Morgan works at a frenetic pace by the kitchen sink, doing his "cooking." He turns on the faucet, shuffles bowls, fills a ladle with water, empties it, fills it again.

He doesn't look over to the breakfast table, where a stranger is talking to his father. New people create enormous anxiety.

He scampers about the house, a tornado with blond hair and brown eyes. He runs downstairs to swing. He's out the door and climbing a tree faster than a squirrel. Then he's back inside, hanging upside down on the back of a couch.

He eventually approaches the table. "Pee-yoo," he tells the visitor. "You smell like a poo." His rhyme is innocent; he's parroting what he's heard from his brother.

This is Morgan's world. But Morgan isn't in his Terrible Twos — he's 9.

He was born with Fragile X Syndrome. The disorder is the most common form of inherited mental impairment, with symptoms more severe in boys.

Stephen Warren, a human genetics specialist at Emory University's School of Medicine in Atlanta, has studied not only the cause of the disorder, but knows the impact it can have on a family.

"Childhood disorders are very stressful for parents," Warren said. "One difference between physical illness, such as childhood cancer, and mental retardation is that people still don't talk freely about it. It's still a stigma."

But Elly and Michael Scott were very open.

When Morgan was 3, the couple wrote a letter they sent to 200 people describing their son's condition. They said the ensuing support from friends, family and the community at large has been invaluable to them.

"We couldn't do this on our own," Michael said.

The Scotts understand well the pressures of raising a Fragile X child. Their world would have been chaotic enough with three little boys — Evan is 5, and Will is 2 — but the chaos is heightened by Morgan's disability.

The Scotts had sensed there was something wrong with their first-born child even before a geneticist diagnosed him. Morgan didn't clap his hands like other toddlers. Or wave bye-bye. While other kids sat quietly, entranced by television, Morgan stood nose-to-nose with the screen and shook his hands violently. Then he abruptly turned and walked away.

The Scotts were devastated when the doctor finally gave them the news.

"I've had a few 'out of body' experiences in my life — my wedding day, the birth of my son," Michael said. "And then there was the day we were told about Fragile X. You find yourself grieving for all the things your son would have been."

Developmental delays are common among Fragile X children. Morgan couldn't speak until much later in life. His parents learned to interpret his wants through his smiles and tears.

The Scotts realized that if they intended their son to grow up and live independently one day, they would have to do all they could for him. That included vigorous therapy and experimenting with a slew of medications.

Morgan is now in the second grade. He can write the first two letters of his name. He can't read typical second-grade books, but he knows hundreds of words by sight. He can read a "stop" sign. And "Moe's Southwest Grill."

"It's almost like memorizing the dictionary," Michael said.

Patience is never a child's virtue, but in Morgan's case, it is a forceful enemy. Homework is challenging.

"The hardest thing is patience," Michael said. "And attention to task."

Before Morgan began taking the anti-depressant, anti-anxiety drug Zoloft, Michael and Elly had to strait-jacket hold him in a barber's chair to get his hair cut.

Morgan has an exaggerated sense of sensory processing and moves around a lot to regulate his system. He doesn't take directions well, and he reacts adversely to large crowds and unfamiliar places.

On a flight to California last summer, he kicked the seat in front of him for an hour. Michael apologized continuously to the passenger, perhaps annoyed at such discomfort in the first-class cabin. Morgan's disability translates into lifestyle decisions that don't arise in other families. The Scotts can rarely go anywhere as a family.

Morgan has a hard time waiting in lines — at the airport, at amusement parks, anywhere.

Michael and Elly were able to take Morgan to Disneyland because there are separate lines for special-needs kids. But when they attended Michael's brother's wedding in Paris, they left Morgan behind.

At the pool, Morgan often cuts into lines for the diving board. Elly has overheard others calling her son rude.

"People look at us and think we can't control our kid," she said. "Because Morgan looks perfectly normal, they don't know that he has a mental impairment."

In California, the Scotts took Morgan to a Target store because that was a familiar place for their son. Morgan finds solace in routine. They let Morgan start the car sometimes as a transition from home. It helps him understand the concept of going out.

Elly said she sometimes feels overwhelmed. There are days when she cries. She calls Michael and says, "Morgan's turned into an octopus." That's the couple's term for when their son is uncontrollably all over the place.

Three or four times a month, Michael travels for his marketing firm.

"That can be difficult when he's away from home," said Elly, who added that she feels lucky to have a supportive husband. There's only three places she can go with all three of her boys: the grocery store, to Target and to the neighborhood swimming pool if it's not too crowded.

Morgan is a strong swimmer and loves the water. But at the pool, he sticks to himself while brother Evan quickly makes friends.

Elly keeps close tabs on Morgan. He could unintentionally harm other children by grabbing onto them and pushing them under water. He picks up other people's towels or walks away with other children's flip-flops.

Sometimes, Morgan wanders from the water and into the parking lot with no fear of moving cars. Elly runs out to gather her son.

"It's hard for me to know how different a normal 9-year-old would have been," she says. "This is all we know."

Morgan, finally exhausted from a morning of expended energy, lies down on a plastic chaise, a beach towel wrapped about him.

"Are you tired, sugar bear?" Elly asks. Morgan doesn't answer. He puts his head down, and for the first time that day, he is perfectly still.