Stokes left England's Test squad midway through the series against Pakistan.
Now, it is understood that the England all-rounder felt mentally disturbed over a news from New Zealand and had to immediately fly back home.
Read Also: Mohammad Abbas opens up on Ben Stokes dismissal at Old Trafford
Gerard Stokes, Ben's father, a former Kiwi rugby player, has revealed that he is suffering from brain cancer.
"I didn't sleep for a week and my head wasn't really in it," Stokes junior told the Weekend Herald on arrival. "Leaving [the team] was the right choice from a mental point of view."
The England star is currently under isolation as per New Zealand government's necessary regulations amid the COVID-19 pandemic.
The 64-year-old Gerard confirmed that he was diagnosed with the illness in January after his return from South Africa where the entire family, including his wife Deb and eldest son James, watched Ben play the four-Test series.
"Stokes senior was admitted to hospital in Johannesburg ahead of the Boxing Day test due to a brain bleed for which he required surgery. It was reported at the time as a 'serious illness'. Further tests on his return to New Zealand revealed cancer," the report from nzherald.co.nz further stated.
"They had to assess how I travelled and from that, they discovered I had a couple of tumors on my brain as well," Gerard said.
"So, basically brain cancer. How that came about nobody knows but obviously I've had a few bangs on my head through my life so that's probably contributed to it," he added.
It was only seven years ago that Gerard returned to New Zealand after coaching professional rugby in England for a decade. A qualified builder, he led a large team that worked with Rolleston Prison's inmates, a role which he said made him empathise with indigent people.
Ben was only 12 years old when he left for England with his family and is now among the most renowned cricketer from the adopted land.
(Inputs from nzherald.co.nz)