Is this sentence for my biography a run-on?

I'm writing a biography and just want to know if this is a run-on:

Had they not survived, the man we know as Alexis de Tocqueville would not have been born, nor the immense accomplishments that made him who he was.

This sentence is grammatically incorrect for reasons other than you think: you have a misplaced modifier. The man is not the "they" you are talking about in the first part of the sentence.

Had it not been for the survival of "whoever 'they' is," the man we know as Alexis de Tocqueville would not have been born, much less been able to complete the immense accomplishments that make him memorable today.

Ok, how does this sound. And the they refers to his parents that are mentioned in the previous sentence that I had not shown.

Had they not survived, Alexis de Tocqueville would have never been known, nor his immense accomplishments that make him memorable to this day