Sentence:  Prince Harry may yet turn out to be the crown's best insurance policy. By marrying Meghan Markle, he is linking royalty with a 21st-century celebrity who has a <WSD>backstory</WSD> that many people in Britain can identify with. 
Meaning of the word marked with <WSD> tags:  The previous life and experiences of a person, especially a character in a dramatic work, but also a real-life person.