Jane Austen obviously did not know about the work of monk-geneticist Gregor Mendel -- for one thing, she died a few year before he was born, and decades before he began quietly drawing charts of pea cross-breeding in the monastery garden. Nor do Jane's books show much interest in the scientific advancements of her day. Nonetheless, her characters, which (for the purpose of this post) conveniently come with siblings and parents, show a quite credible adherence to Mendellian gene patterns.Consider: in PRIDE AND PREJUDICE, Mrs. Bennet is silly and dumb, Mr. Bennet intelligent and sarcastic. Of the five daughters, two are silly and dumb (Lydia and Kitty), one silly and intelligent (Mary), one intelligent and sarcastic (Elizabeth), and one intelligent and calm (Jane), much like her mother's brother. If silliness is thus dominant and Mrs. Bennet is carrying an Ss combination (that brother got two ss from their parents), then this is a plausible genetic distribution among their overspring. The same for intelligence, with calmness and sarcasm recessive.
You can do the same with the three daughters in PERSUASION. And MANSFIELD PARK, with its four siblings, is a perfect Mendellian inheritance pattern for sensitivity as a recessive gene (only Edmond, 25% of the offspring, has it).
Of course, personality traits are not that easy accounted for by single genes. But that's not my point. It is, rather, this: Good novelists intuitively understand the composition of real families. And real characters -- rounded, believable, interesting -- do not exist in a vacuum. They have, or at least had, families, which they were partially shaped by.
Often, SF does not do this very well. Too many protagonists exist in a familial and genetic vacuum. True, if your hero is off exploring a new planet, he probably does not have the entire family along so we can observe them. But she does have memory (good or bad), and using it to create a wider past can help characters seem more believable. Better yet, root the character in a family -- there is no better way to evoke more aspects of your fictional society. When I first read Ursula LeGuin's THE DISPOSSESSED, it was a revelation to me how much she solidified her society by including families in it. As does China Mieville in the more recent EMBASSYLAND.
At some level, Jane Austen knew what she was doing. But, then, she always did.