That bit of information didn’t just pop into existence “ex nihilo”, it came from surviving letters\diaries of the local gentry. I guess TJ could be the father. I wouldn’t care much except the way it was “surfaced” back in the Clinton years, to give Slick “cover” for his behavior. Given that, I’ll push back until there irrefutable evidence TJ did it.
I guess Randolph or one of his sons could have been the father -- it may even be likely -- but the way TJ's defenders just wheeled around and decided it had to be RJ when the other possibility was finally excluded makes me at least a little suspicious of the new version.