She said she didn't start too quickly and managed to conserve energy, which helped her win the race.
"It is probably the first time I have done what [my running coach] wanted me to."
Gibbs said it was great to have her coach Barry Ellis there supporting her. She said some of her family members were also there, running the marathon.
"My son and daughter-in-law are still out there and they have a lot of hurt still to go," she said after her race.
Meanwhile, Ruthe added to her family's success at the Rotorua event by finishing second.
Her father won the men's race in 1984 and her mother came second in the women's race in the same year.
"I did it in the same time as my mum - two hours 48 minutes," Ruthe said. "I had to make it in under 2.49 so she couldn't say she ran faster than me."
Wellington's Katie Kemp finished third, just over a minute behind Ruthe. Seven women runners finished under three hours on Saturday, up from two in 2013.
The Rotorua Marathon doubled as the Athletics New Zealand Marathon Championships with Gibbs taking the New Zealand title.
In the men's race, Japan's Masataka Uchino became the second overseas runner to win the event.
Uchino decided to take part in the 50th Rotorua Marathon after a friend recommended it and was neck and neck with three-time champion Phil Costley until the 32km mark, where he opened up a big gap, to win in 2hr 27min 45sec.