The BBC's high-profile economics editor, 45, went out with both politicians in the 1990s, when she was in her 20s.
Mr Miliband revealed in July both he and Mr Balls previously dated the journalist, but insisted the relationships were "a long time apart".
The TV journalist said she hated to see stories about her own past make the headlines.
Asked whether she minded when her life became the news, she said: "I hate that. And I'm rather amazed people should be interested in things that happened a long time ago.
"If people think about their own lives and people they might have gone out with briefly in their 20s, and what role those people play in their lives now: I think they would realise it really does not impact on my day-to-day work."
The mother-of-two, whose partner is the journalist John Arlidge, also said she is "particularly nervous on Budget days" because of the pressure to reach judgments on figures without the time to digest them.
"I live in fear of getting it wrong. You're live on TV and you pretty much have to respond almost as the Chancellor is speaking. And you're supposed to be tweeting, doing live commentary and writing a blog at the same time," she said.
The broadcaster, whose father was the performer Michael Flanders, said she had not inherited his talents, saying: "I'm not as funny as he was: I'm funny for an economist, but that's not saying very much."
She added: "I sometimes get rather envious of people I meet who went to see my father's show in the 1960s because it had finished before I was born."
Mr Miliband, who later went on to marry Justine Thornton, previously told a magazine: "We did both date her but there was a long time apart between me and Ed.
"Stephanie and I don't have any problems running into each other now."