He said their children had "always" tramped with them, joining them on the Heaphy and Waikaremoana tracks and "other great New Zealand walks".
"Lachlan did the Milford Track with us when he was 11 years old.
"They always carried their own packs."
Yet Mr McKinnon says the additional challenge of altitude made the Kilimanjaro climb "quite different".
"At that height it was incredible, I got quite unwell."
On summit day, the McKinnons had to leave camp at 11.30pm in order to reach the peak at 8.30am, in time to see the sunrise and get back before dark.
"I was physically exhausted, I had no energy left," Lachlan said.
"You couldn't breathe."
By that stage, he and Laura were taking "two steps at a time" over the final stretch.
Porters carrying 20kg packs on their heads also inspired the teens to push on to the summit.
Yet despite the pain and a little cloud, reaching the top was spectacular and absolutely "worth it", Laura said.
The siblings said seeing the poverty of the area changed their perspective.
"The fact that you could see people wearing sandals and jeans, climbing up joking and laughing... we take what we have for granted," Lachlan said.
The climb took the McKinnons seven days in total.
Mr McKinnon says he is "especially proud" of his children for rising to the challenge.
The youngest New Zealander previously to have scaled the peak was 15-year-old Sarah Hall, daughter of late mountaineer Rob Hall.
She reached the summit with her mother Jan Arnold last year.
Mr Hall was a New Zealand mountaineer who perished while guiding an ill-fated expedition on Mt Everest in 1996.
He died nine weeks before Sarah was born.
