Answer by taking a quote from the following article:

Hillary was born to Percival Augustus and Gertrude (nee Clark) Hillary in Auckland, New Zealand, on 20 July 1919. His family moved to Tuakau, south of Auckland, in 1920, after his father, who served at Gallipoli with the 15th (North Auckland) Regiment, was allocated land there. His grandparents had emigrated from Yorkshire to northern Wairoa in the mid-19th century.

Hillary married Louise Mary Rose on 3 September 1953, soon after the ascent of Everest; he admitted he was terrified of proposing to her and relied on her mother to propose on his behalf. They had three children: Peter (born 1954), Sarah (born 1955) and Belinda (1959-1975). In 1975 while en route to join Hillary in the village of Phaphlu, where he was helping to build a hospital, Louise and Belinda were killed in a plane crash near Kathmandu airport shortly after take-off. In 1989 he married June Mulgrew, the widow of his close friend Peter Mulgrew, who died on Air New Zealand Flight 901 in 1979. His son Peter Hillary also became a climber, summiting Everest in 1990. In May 2002 Peter climbed Everest as part of a 50th anniversary celebration; Jamling Tenzing Norgay (son of Tenzing who had died in 1986) was also part of the expedition. Hillary's home for most of his life was a property on Remuera Road in Auckland City, where he enjoyed reading adventure and science fiction novels in his retirement. He also built a bach at Whites Beach, one of Auckland's west coast beaches in the former Waitakere City, between Anawhata and North Piha; a friend called it Hillary's place of solace, where he could escape media attention. The Hillary family has had a connection with the west coast of Auckland since 1925, when Louise's father built a bach at Anawhata. The family donated land at Whites Beach that is now crossed by trampers on the Hillary Trail, named for Edmund. Hillary said of the area: "That is the thing that international travel brings home to me - it's always good to be going home. This is the only place I want to live in; this is the place I want to see out my days."

what was this connection?
Louise's father built a bach at Anawhata.