The current Father of the House is Gerry Brownlee, List MP and formerly member for Ilam.
The current Mother of the House, as the longest continuously serving female MP, is Judith Collins.
[1] The position is usually determined by continuous service, not aggregate time in parliament or the earliest year of entry.
For example, Damien O'Connor has served as long as Brownlee, and entered parliament a term earlier (in 1993), but since he lost his seat in 2008 he is not considered a joint Father of the House.
When more than one MP have served equally long periods, the title is usually assigned to whoever was sworn in first, a process which happens alphabetically by surname.