Comics have long struggled with the issue of characters aging. Some heroes get frozen in ice to stay young, some get de-aged magically, and some are Batman.
And some, like Black Canary, get split into two characters and simultaneously become some of the worst parents in comic book history.
Pre-Crisis, Dinah Drake Lance ditched the Justice Society and Earth-2 after her husband Larry died, because she couldn’t bear to stay in a universe that reminded her of him. Upon her arrival in Earth-1, she discovered a newfound power – her Canary Cry – but shrugged it off as normal superheroic weirdness and went on with her life (read: shacking up with Green Arrow).
This worked fine in 1969, but by 1983 DC realized that Dinah’s World War II background put her in her 60s at the youngest. Instead of taking the easy route and chucking her in a Lazarus Pit or whatever, they unleashed this doozy: years ago, Dinah and Larry had a daughter, Dinah Laurel Lance. When she was a newborn, JSA villain the Wizard cursed her with her Canary Cry – not something you want a baby wielding. To prevent baby Dinah from crying the house down around their heads, Johnny Thunder got his Thunderbolt to move her to the Thunderbolt dimension, unconscious but aging, until a cure could be found. (So, in a coma, basically.) Then, because her parents were understandably sad about this, the Thunderbolt erased Dinah Jr.’s existence from their memories.
Years later, when Dinah Sr. was making her move to Earth-1, she discovered that she was dying of the same radiation that had killed Larry. Johnny: “Is this a bad time to mention that you have a kid that only I know about?”
Our heroes hit upon a “solution”: they transferred Dinah Sr.’s memories to Dinah Jr.’s nubile young body, effectively ensuring that Dinah Sr. could continue her long, happy life, while her daughter would never be permitted to have one of her own. Also, she’d have a mysterious, destructive power that she couldn’t account for. Also, she’d think her father was her dead husband, and, like, have memories of marrying him and sleeping with him and stuff. Gross. To give Dinah Jr. credit, she took all this pretty much in stride when Superman spilled the beans (oh yeah, old Supey knew all about it), but she’d also never seemed to notice that she was physically 30 years younger than she thought she was, so in general she seemed pretty willing to roll with the punches?
Anyway, this was all tossed out in the Crisis two years later, so there’s only one real takeaway: NEVER EVER LET JOHNNY THUNDER BABYSIT.