February 23, 2010— — At 5 feet 0 inches tall, 13-year-old Daniel Clark from Harlem, New York, is considered one of the most easily bullied boys simply because he is smaller than his classmates.

“He was attacked and robbed five times outside of school,” said Daniel’s father, Daniel Clark Sr. “Every time he leaves the house, you have to think, ‘Oh my God, I hope nothing happens to him.'”

Daniel has always been in the bottom tenth in terms of height. At his previous school, Daniel said he was kicked off sports teams, teased, and had to work harder to prove his talent because of his height.

“I may be small in appearance, but not in personality,” said Daniel.

Unlike his son, Daniel Clark Sr. was already 6′ tall when his son was older. And even though his mother is 5′ tall, doctors aren’t sure how tall Daniel will get. His father says it’s hard to see his son feel so held back because of his size.

“He’s a nice guy who’s on the small side in stature,” Clark said. “We both thought he might be going through a growth spurt.”

Parents often worry about their child’s slow growth, and this fear is even greater for boys, according to a study published in the British Medical Journal.

Growth spurts in boys begin around age 13, but they can begin as early as age 10 or as late as age 16. And on average, girls have their biggest growth two years earlier than boys, says Dr. Richard Besser, senior health and medicine editor at ABC News.

However, every child has different growth potential, says Dr. Joseph Zanga, chief of pediatrics at Columbus Regional Health Care System in Columbus, Georgia.

“Even a child in the 50th percentile can be normal,” he said, “but if he has been in the 90th percentile his entire growth life and then drops to the 50th percentile, normal is not necessarily normal.”

Helping children grow

Children are generally considered short if they are shorter than 98.8 percent of other children of the same sex and age, according to the Food and Drug Administration. While factors such as proper nutrition and plenty of physical activity help ensure a child grows normally, genetics also plays an important role in determining how tall a child will be, Zanga said.

“If no one in my family is over 5 feet tall, I’m happy that my son has reached his potential,” Zanga said. “If everyone in my family is 6 feet tall and my child doesn’t look like he’s going to make it, I might be worried.”

According to Besser, parents should talk to a pediatrician if their child is growing less than two inches per year, if he or she is neither gaining nor losing weight, or if he or she has frequent coughs or infections.

Serious growth stunting for some children includes malnutrition, hypothyroidism, and heart and lung disease. Pediatricians use medical histories and physical exams, which may include X-rays to examine bone aging, to determine what is stunting growth in some children.