Coming up with characters is long and complicated.
I can say my brother was a seneschal, for instance, and no one will know what I'm talking about. It will get boring if people say "my dad was a blacksmith" or "my dad was the best blacksmith" or "my dad taught me to make horseshoes".
I looked to historical fiction and non-fiction, and there wasn't much help there in most novels, although I found family showed up more often in stories that didn't involve magic.
Recently, I've read the first book of the Erevis Cale trilogy. Cale's family is not mentioned, but he has good friends (some of whom die, one of whom gets kidnapped). His two friends (Fleet and Riven) have almost no family or friends. Fleet, at least, is a real friend to Cale. Riven's only "family are a pair of dogs.
Then again, they're rogues.
His employer is a minor sorcerer whose father was killed in some kind of magical accident. I'm seeing a trend here.
In the Black Boquet, there's a rogue (name forgotten) whose old father gets kidnapped, but he did have friends. They died in chapter one.
He meets up with a ranger (no mention of her family, few mentions of her adventuring guild) and an evil monk (likewise).
In Cloud of Swallows, three Americans travel to Japan. Of the three, Matthew Stark's girlfriend was killed (and he's seeking revenge), and I vaguely recall him being an orphan. Emily actually had a family, which featured prominently ... in flashbacks. Brother Cromwell's family is not mentioned, not even once. The Japanese heroes have family connections but the villains did not. Some families were wiped out in the course of the novel.
In Romance of the Three Kingdoms, early on (in the more interesting part) most of the main characters have brief mentions of their family.
Once Liu Bei goes off to fight the Yellow Turbans his ancestors, real siblings and so forth are never mentioned again. Indeed, his family gets a sentence or two ascribed to them. (Of course, he is a very distant relative of the imperial family, which gets its own paragraph later on, and drives him to his destiny, or so he believes.)
He married three women, two of whom get virtually no mention in the book (other than one disappearing in a major battle).
They never mentioned when his oath brothers Zhang Fei and Guan Yu got married. Their children basically show up, fully grown and trained, in their first major battle.
Cao Cao's ancestry is touched upon. He was descended from Cao Song, who was adopted by a eunuch (Cao Cao hates eunuchs). His father gets killed, and Cao Cao gets really angry and starts massacring peasants because of that. (It's a more complicated story, actually. For starters, he only used his father's death as an excuse to start massacring peasants.)
They never mentioned when he got married, but all of a sudden he has an "eldest son" in that character's first (and only) major battle.
His first wife dumped him after he lost a battle on the Yellow River, in which her only son was killed because Cao Cao was too busy sleeping with a lady he just met instead of paying attention to war. This is mentioned in historical documents, but not in Three Kingdoms.
Even in Big Fish, a non-historical novel (with no relation to the movie of the same name) the main character doesn't even have a first name. He's married, but has no kids and his family is not mentioned once. His sidekick's family is not mentioned once.
It seems to me the only time someone's family is mentioned in the kinds of literature that might inspire people who play DnD is if someone is famous (by taking part in a battle or being really skilled at something) or if their family gets kidnapped. Or if they're noble, in which case their family still might not be all that important.