When every character has a sob story, no one does.
One of the main faux pas that I see young writers make is this idea that that they need to give every character a tragic backstory. There can be no happiness in the past for our main characters. Their childhoods must be steeped in sorrow to make them deep and tragic because being deep and tragic makes them interesting and no. That is just not true. A character can be interesting even if they had a perfectly normal and happy childhood.
That’s not the reason why I’m talking about this issue, though. I’m bringing it up because of a very real problem that comes with giving everyone a sob story: when every character has one, then no one does.