The eldest son of the 13 siblings who police say were held captive by their parents attended college for years but did not seek help.
The straight-A student, who went to a community college in California, did not draw attention to himself, according to reports.
The student, now about 26-years-old, did not divulge information about his parents David and Louise Turpin, aged 57 and 49, who were charged with 12 counts of torture, 12 of false imprisonment, six of child abuse and six of abuse of a dependant adult.
A spokeswoman for the Mt San Jacinto College said the student, who would be driven to classes by his mother, was on the president’s honour roll in 2015 and 2016.
ABC News obtained a transcript which showed he attended college between 2014 and 2016 and earned A grades in several classes, including algebra, guitar, public speaking, English fundamentals and freshman composition.
Former classmate Marci Duncker said the sibling had “one of the most sad faces” and that he was “always quiet and alone”.
Police were alerted to the family after one of the daughters, a 17-year-old girl, escaped and told officers her siblings – aged between two and 29 – were being held captive.
The remaining 12 siblings were found by authorities “malnourished and very dirty” and shackled to their beds with chains and padlocks.
They were all taken to hospital after they were freed from their home in Perris. Authorities claim the abuse was so long-running that the siblings’ growth had been stunted.
Speaking of the eldest son’s behaviour while at college, Gale Kelley, a trainer for the International Association of Trauma Professionals, said his reluctance to report his parents was understandable.
She said: “They were born into this. This was normal for them. Some of them may not even realise they’ve been abused.
“These children have been living in isolation so they only know what they know.”
She said abusers would often tell children not to talk about what happens at home to those on the outside.
“We don’t know what kind of duress they were under as far as threats,” she added. “They’re still seeing the world through the eyes of a scared little kid who is in constant danger.”
The parents deny all the charges against them.