Tragic backstories are for edgy teens. Just forget about one and write the story.
While I'm unhappy with forcing things, this is also not a good take. Because first of all: How do you define a "tragic backstory"?
I have once read a novel, in which the MC started the story feeling guilty as hell, because she killed a person - accidentally, but she saw herself at fault. What had truly happened? Protagonist invited a young woman she met at a Weight Watchers meeting to ride home with her, because she found her respectable, hitting her goals and such. They talked in MCs car, it was about some random soup recipe that supposedly helped Weight Watchers woman, so she took off the seatbelt to grab her purse from the back and fetch the recipe (or something to write it down on, I kind of forgot about that bit, it's been like 15 years). Right at that moment, the truck in front of them lost cargo, because it wasn't closed correctly - it was a moving truck or delivery for a furniture store or some shit, at least I remember they were hit by a kitchen cabinet. Tomato soup woman flew right through the windshield when they rolled over, while MC was hurt, but alive and well in the end. Nobody found her guilty of anything, but she herself felt guilty and the victim's family wasn't fond of her either (understandably). The whole story then hinges on her idea of fullfilling a bucket list the mid-twenty Weight Watchers woman had, as MC was older and going to turn 30 soon and the list was about things to be done before 30. In the midst of this, she may or may not fall in love.
Now, the book is definitely one that would be put in the "Jousei" category if it were a Manga, so it might not be to your liking, but this is definitely something I would consider a "tragic backstory". The entire story is all about it as well, with the MC trying to work out the trauma of what has happened and move on from her guilt, with the bucket list as her medium to get to work, hence why the novel is called "The Wishlist".
Do you consider that "for edgy teens"?
Backstories are everything that has happened before the plot starts, no matter how old the character might have been. Every character needs a bit of backstory, otherwise it won't have a character with motivations. Of course, there's backstories that are meant to break the limit of how much can be possible, but even that, if incorporated fully, serves a purpose. I would even go as far as to say, in order to get a certain type of character in the main story, with specific goals, personality traits, set values and capabilities, you will have to make his backstory considerably "tragic", in order for it to even work. Because "backstories" are nothing but experiences, and sometimes, you need experience for certain things, even if it's just the old: "I've experienced a certain amount of pain, which is why this won't stop me, thus I will be the first one to make it, for I have lived an entire life already and don't have to do this as my first experience, only to be unable to cope and die, like the others."