"[T]his was not a case of fortitude or of resignation only. A submissive spirit might be patient, a strong understanding would supply resolution, but here was something more; here was that elasticity of mind, that disposition to be comforted, that power of turning readily from evil to good, and of finding employment which carried her out of herself, which was from nature alone. It was the choicest gift of Heaven..."
-- Anne Eliot's thoughts about Mrs. Smith's innate personality in Persuasion
The book opens with just such a clash. The marital fortunes of the three Ward sisters vary a great deal, and so do their tempers and personalities. The imprudent marriage of Frances Ward leads to an "absolute breach" between the sisters. Mrs. Norris, as Austen says with delightfully wry understatement, has a "spirit of activity" and she sends a scolding letter to Frances. Frances, nettled, writes back an angry letter which Mrs. Norris "could not possibly keep to herself."
Lady Bertram, the former Miss Maria Ward, has a "temper remarkably easy and indolent." In giving up her sister Frances, she is guided, as she is in all things, by the meddling Mrs. Norris. The personality dynamic between Mrs. Norris and Lady Bertram has significant consequences throughout the story.
The word "personality" wasn't around in Austen's time, nor was the term "nature versus nurture," but the concepts certainly were. In addition to analyzing people in terms of their "tempers," the term “disposition” was frequently used to describe innate personality.
Austen herself remarked in a letter about her great-nieces: “How soon, the difference of temper in Children appears! — Jemima has a very irritable bad Temper (her Mother says so) –and Julia a very sweet one, always pleased & happy.-I hope as Anna is so early sensible of its defects, that she will give Jemima’s disposition the early & steady attention it must require.” Likewise, when discussing her brother Charles's daughters, she wrote: "[Cassy] ought to be a very nice Child - Nature has done enough for her - but Method has been wanting... She will really be a very pleasing Child, if [her parents] will only exert themselves a little. - Harriet is a truely sweet-tempered little Darling."