CLEBURNE (CBSDFW.COM) – Six-year-old Andy Barrow loves to read, but his older brother Alex would rather play. One thing the two brothers from Cleburne have in common, however, is autism.

“He lost all speech. He just wasn’t there,” said Rachel Barrow about her 8-year-old son Alex.

She said she knew something was different when he was a toddler, but with younger son Andy, it wasn’t as obvious.

“He had language, but he would memorize lines from movies and he would script them word for word,” Barrow said.

A new study in the journal Pediatrics found siblings of a child with autism are 20 percent more likely to get the disorder.

Autism doesn’t just strike randomly. Genetics are thought to play a role, and diagnosis skews heavily toward boys – of the 132 children in the study who had autism, just 29 were girls.

The recurrence risk was previously thought to be between 3 percent and 10 percent, but “previous research was limited by small sample sizes” and bias, the study says.

“There is a very strong genetic component to autism and that’s something people have to keep in mind,” said Dr. Joyce Mauk, President/CEO and Medical Director of The Child Study Center in Fort Worth.

The nonprofit organization helps diagnose and treat children with autism. Mauk says the study is important because spotting the disorder early makes a big difference in a child’s development.

“Any sibling should be monitored carefully and should be screened as recommended by the American Academy Pediatrics at their pediatrician’s office,” Mauk said.

The Barrows wouldn’t change a thing about their family.

The boys have been going to The Child Study Center for treatment. In just six months the two have each reached meaningful milestones, Barrow said.

“Alex went from having one or two words whispered to now talking three to four words at a time. Andy can now have a conversation without scripting,” she said. “I wouldn’t trade what we’ve been through. It sounds crazy, but I wouldn’t not want to have Alex and Andy in our life.”

Parents with children who have autism are encouraged to look for signs in the first few months after birth.

According to the Center for Disease Control, autism may be more likely in a child who doesn’t respond to his or her name; avoids eye contact and wants to be alone; has delayed speech and language skills; and flaps their hands, rocks their body or spins in circles.

The Pediatrics study included 664 children, 132 of whom were diagnosed to have autism. Seventy-eight children had a more mild developmental disorder.