All superhero families are the result of unplanned lore building

>In the early days, there was the superhero, let's call him A-Man
>A-Man is a huge hit, but back in those days, every superhero should have a younger sidekick, lets call this A-Boy
>The duo continue to be extremely popular, but now the readers are getting a bit bored of the same old routine, so the writers invent a new character who is more or less the same, let's call this A-Girl
>The series continues to thrive but then it gets boring again, so lets introduce the evil dark version of A-Man, we'll call him B-Man

At this point, everything is fine, it's just a goofy series, there's no real continuity between anything, it's more or less akin to Spongebob or Simpsons. Episodic fun.

>Trends are changing, now people want deep serious stories with tight continuities, so lets get rid of all the lame spinoff characters and return back to just A-Man (this time with a black suit)
>The reboot is extremely popular, so to give the fans a bit of love, lets bring in one of the legacy characters
>But we can't just introduce them out of the blue! This is serious story, we have to integrate it
>A-Boy is now actually a real person with a life and personality outside of being just A-Boy
>Kill A-Boy for the shock value
>But wait, A-Boy was popular, bring him back
>A-Girl now marries A-Man because serious gritty stories demand love... but lets also kill A-girl, for shock value!
>B-Man is revealed to be A-Man's secret brother, separated at birth!
>A-Boy is growing up (remember, tight continuity, many years have passed), he doesn't want to wear a skimpy leotard anymore, he wants to be his own man, now he is X-Boy

If you had designed a superhero story with a family concept from the get-go and not just A-Man, none of this would ever happen.
None of these characters are real outside of A-Man, they are all just desperate ripoffs, cashing in on the popularity of A-Man, but who cannot exist without A-Man