Jane Austen's emphasis in Pride and Prejudice illustrates the close, indeed inextricably close, connection between culture and behavior. Darcy has the manners he has--that of a gentleman, but one who has never had his deportment questioned--because of the culture of his times. He was a man of privilege and great wealth, and everyone around him knew this to be so, even headmasters, masters, and professors at his schools would know his privileged state and act accordingly. As a point of comparison, such manners as Darcy had would look ridiculous to us in today's culture in almost any country effected by Western civilization.
Elizabeth's secluded life as a country gentleman's daughter surrounded her culturally with the freedom to develop her own mind and mental traits without the guidance or influence of more formalized urban aspects of the culture of the era. As a result, she learned to quickly form her own mind--with or without due reflection and consideration--and thereby expressed the strength of mind the culture valued, though valued usually in men!
These two examples show how culture influences the characters on the personal level; Charlotte and Wickham show how culture influences characters on the social level. Charlotte is strongly influenced by the culture--one which requires women to be married for various reason, including independence and income--in her choice to marry Collins. She says of him:
I ask only a comfortable home; and considering Mr. Collins' character, connections, and situation in life, I am convinced that my chance of happiness with him is as fair as most people can boast on entering the marriage state.
The narrator has prepared for Charlotte's sentiments by explaining the cultural influences that led to Charlotte's social choice. The narrator explains that for women who do not have enough wealth to attract men of higher caliber than Collins, marriage is the most, or "only honorable," social choice for happiness and for income for a "well-educated” woman:
[M]atrimony, marriage had always been [Charlotte's] object; it was the only honourable provision for well-educated young women of small fortune, and however uncertain of giving happiness, must be their pleasantest preservative from want. [And] Miss Lucas, ... accepted him solely from the pure and disinterested desire of an establishment [independent home of her own], ....
Wickham's social choices are similarly influenced by the culture of the times. He must have an income so that he can continue to live the life that being the privileged son of the steward of the Pemberley estate had accustomed him to--this meant he must have an income of significance and one that comes with status, not with work. Hence, Darcy senior's provision for Wickham to become a clergyman and, hence, Darcy's provisions for him to buy an officer's commission in the Regimental Army. Wickham's other option, one which he pursued ardently, was to marry a lovely young lady of wealth and charm; thus he turned his attention first to Elizabeth, then to the much wealthier young heiress with ten thousand pounds.