Nate was deflowered by Fiona Kleinschmidt. Although when that happened, Nate was 15 and Fiona 32, the given year of Fiona's birth is 1956, and Nate's 1965, and that makes Fiona 9 years older than Nate instead of 17.
In Episode 6, Season 2 is first mentioned that 32 year old woman that deflowered Nate. Nate's birth year is mentioned repeatedly, and Fiona's birth year is mentioned in Episode 6, Season 5.
A teakettle whistles, yet as Ruth pours the water from it, it is a simple ceramic pot, not one with a whistle.