He had dreamed of becoming a marine biologist and was to travel to Turkey weeks later to pursue his studies.
But when security forces moved in to disperse the protesters he was shot dead along with hundreds of others in the worst mass killing in Egypt's modern history.
The Sonbols' troubles began months earlier, in December 2012, when Amany's husband was hustled out of their Dubai apartment by plainclothes police, accused of forming an illegal branch of Morsi's Muslim Brotherhood in the Gulf emirate.
"I lost my son in a brutal massacre committed by this (Egyptian) government. He will never return and I have no idea when my husband will return," Amany told AFP at the family's elegantly furnished apartment in Cairo.
The army toppled Morsi after massive protests demanding his resignation, with critics accusing him of betraying the 2011 "revolution" by monopolising power in the hands of the Brotherhood and failing to revive Egypt's crippled economy.
Morsi's Islamist supporters responded with their own protests, in a standoff that peaked that sweltering August day, when security forces stormed Rabaa al-Adawiya, clearing the square but leaving the country bitterly polarised.
Since then a sweeping government crackdown has left more than 1,000 people dead --including security forces targeted in reprisal attacks -- and more than 2,000 Islamists, including Morsi and the Brotherhood's top leadership, languishing behind bars.
"They are a bunch of killers. You saw Rabaa. There is a difference between dispersing protesters and massacring them," said Ahmad's sister Huda.
"Which is why they can't be forgiven. It is not about my brother or my father, it is about those thousands they have massacred. And that is why we will protest until this government goes."
'In death too he looked calm'
For Ahmad, Morsi embodied the change Egyptians yearned for after president Hosni Mubarak's three decades of autocratic rule, his sister Sarah said.
But the young man was also drawn to the sea -- his diving equipment is still tucked away in a corner of the family's apartment -- and he worked as a teacher's aide to Edwin Cruz-Rivera, a marine biology professor at the American University of Cairo.
"He was a committed Islamist, but not a hardliner, because he was open to accepting different ideologies," Cruz-Rivera, an American, told AFP.
"We had our disagreements on topics such as religion and morality, but he never blindly followed anything. He was a very driven individual and that (was) reflected in his views, be it on religion or politics."
Amany says her son filled in for his father when her children moved back to Cairo to pursue higher education after several years in the Emirates.
"Ahmad did everything. Whether it is looking after his sisters or buying groceries," she said, as her eyes filled with tears.
Sarah said Ahmad, like so many Egyptians of his generation, was committed to change and willing to take great risks.
"Ahmad had his own mind. He was bold... but the way he was killed...it was brutal. How can the world dismiss such a massacre?" she said.
"In death too he looked calm. Even after 24 hours, when we collected him from the morgue...his face ..his body had this beautiful fragrance. His friend who was with him at Rabaa said Ahmad did not even scream when bullets hit him."
Missing his son's funeral
After Ahmad's father was taken away by the police it was two months before the family had any word of his whereabouts.
"Then he called one day in February. He sounded confused and lost, didn't know where he was," Sarah said.
They soon learned that Ali Sonbol, who had worked as a physician with the health ministry in Dubai for three decades, was accused along with other Egyptians and Emiratis of trying to set up an illegal branch of the Brotherhood.
The conservative monarchies of the Gulf have long viewed the Brotherhood -- a grass-roots movement founded in Egypt more than 80 years ago -- as a threat because of its political activism and advocacy for Islamic governance.
The Sonbols deny Ali is part of the Brotherhood, but say he voted for Morsi in the June 2012 presidential election.
"My father was very popular among his patients. Probably the Dubai authorities thought he may influence them... which is ridiculous," Sarah said.
"What pains my father is that he was unable to see Ahmad ... or attend his funeral. But he is proud of him... He says Ahmad is a martyr."
The Sonbol women say they have little recourse in Ali's case, which is being tried by the state security court. All they can do is wait for the occasional telephone call from the Dubai prison where he may be confined for years.
Badr Abdelatty, a spokesman for Egypt's foreign ministry, said Cairo was in touch with UAE officials concerning the case of all the detainees, but said "we have to respect the UAE laws."
"The reality is that these families have stopped approaching the foreign ministry," he said.