The family of Mohamed al-Beltagi, who used to be the head of the Muslim Brotherhood's party's office in Egyptian capital Cairo, said in a statement on Saturday that his son, Khaled, was arrested by policemen.
It added that police had raided al-Beltagi's house in Cairo on Friday and arrested Khaled, who is 16 years old.
"This is a vengeful act against the rest of the family," the family said in the statement.
Al-Beltagi himself has been in jail for more than a year now, facing charges of inciting violence. His elder son Anas is also in jail.
Al-Beltagi's daughter, Asmaa, was killed in August of 2013 when Egyptian police violently evicted an eastern Cairo protest camp in support of ousted President Mohamed Morsi.
A judicial source, meanwhile, said that Khaled faced multiple charges, including inciting riots, theft, and joining a terrorist organization.
"He was arrested during a protest by the terrorist Muslim Brotherhood organization," the source told The Anadolu Agency on condition of anonymity.
He noted that a laptop was found with Khaled at the time of his arrest along with fliers calling for staging protests during the January 25 revolution anniversary on Sunday.
Morsi, Egypt's first freely elected president, was ousted by the military in July of 2013 following massive opposition protests.
While Morsi's supporters describe his overthrow as a "military coup," opponents term it a "military-backed revolution."
Ever since Morsi's overthrow, Egyptian authorities have maintained a harsh crackdown on his supporters, detaining thousands and killing hundreds.
In December of 2013, Egyptian authorities branded the Muslim Brotherhood, the group from which Morsi hails, a "terrorist" group.