I did study on superhero legacies and the starman one is probably second only to the hawkman one.
Excluding its own members it also incorporates the star-spangled kids, gimmick girls, stripesies, phantom ladies and manhunters through genetics or passing down the torch.
What are your opinions on legacies that intertwine with each other?
Boy-oh-boy are you NOT kiddin'
(An unofficial "Star Family Tree" I found online)
Keep in mind, this is just the family tree that we KNOW of! There's still some secret IDs on this list and it doesn't cover anyone who isn't publically a superhero or something of that kind so there's almost certainly massive branches missing here.
Not sure why you would ask my "opinion" on what is, ultimately, people's private lives. If it works for them, it works for them. It is not my job to comment on who is doing what with whom when the door is locked and the spandex is off.
Now, if you want me to wonder why family trees like this one might HAPPEN in this business, I think its obvious. Same reason firefighters tend to marry firefighters. Not only are superheroes most likely to be around other superheroes a lot of the time, when you get to the point in life where you are relying on people, trusting them to have your back when things get darkest, having to give up your control to someone else. One can only imagine the kind of bonds that creates.
Superheroes often live short lives, and the also often come from broken families. It's only nature that when they find that feeling of comfort in one another that they follow it as far as it will go.