RIVERSIDE, Calif. -- The oldest boy among 13 siblings who authorities say were held captive by their parents had attended a California college for years but apparently never told anyone about his life at home.

Louise Turpin regularly drove her oldest son to classes at a campus of Mt. San Jacinto College in Riverside County and waited outside the classroom for him.

The college said he was on the president's honour roll twice.

Gale Kelley, a trainer for the International Association of Trauma Professionals, said his reluctance to discuss conditions at home was understandable.

She said the conditions were normal for the family and the siblings may not have realized they were being abused.

None of the children have been identified. Their parents have pleaded not guilty to torture and other charges.