What nationality is the surname JENNESS?

Answer 1

answer from ancestry.com -

1. English: patronymic from the Middle English personal name Jan (see Jayne).

Jayne - English: from the Middle English personal name Jan, a variant of John. (As a personal name, Janewas not specialized as a female form until the 17th century.)

1. Possibly an Americanized form of French Lajeunesse.

Lajeunesse - French: secondary surname, also used independently since 1706, from la jeunesse 'youth', hence a nickname for someone especially young, fresh, or naive. It is often translated as Young.