Fun with Ruby Gloom headcanons. These are the parents of the main cast - excluding Scaredy, Doom, and Poe of course - and here's the reasons for why they aren't with their children in that spacious mansion:

Victove Curry (Frank and Len's father)
Victove had to flee the country when it was discovered his experiments and sons, so he shipped Frank and Len off to live in Gloomsville where he knew they'd be appreciated. At the moment, he's busy trying to contact them while still pursued by angry mobs everywhere he goes.

Mr. and Mrs. Spats (Iris' parents)
Iris ran away when she was only a toddler JUST to get away from these two. They're super strict Cyclops parents with only the highest expectations for the ghouls, not to mention gender roles they insist their children follow.

Melancholy and Macabre (Misery's parents)
Melancholy was the matriarch of Misery's family (hence why she's taller) and died of broken heart sometime after her husband died on their anniversary. Misery knows that her aunts are more likely to inherit the title of the new matriarch, but she misses her mother either way.

Penny Dreadful and Chaney the Spirit of Strife (Ruby's parents)
Penny Dreadful is a human woman who was bored in college and decided to perform a demon-sacrifice with some friends (it was a different time). She was offered to the Prince of Strife and Anguish as his new bride, but Penny quickly saw that the prince was lonely and they eloped to the mortal world and had a daughter together. Eventually their relationship went south, Chaney returned to the underworld and Penny hid Ruby is Gloomsville hoping her father would never find her.

Dolce and Sombreron (Skull Boy's parents)
Sombreron's a rebel calaca while Dolce was one of the many women he met on the road and dumped just as quickly as he dated. Dolce was then forced to give up her son when her family demanded she return home, so she threw him into a river which washed him into Gloomsville.