The hottest person in FF7 closely followed by Vincent Valentine, but go figure! Contrary to popular belief, meaning the word of a crazed-lunatic scientist who'll call anything that's successful his progeny, Sephiroth is Vincent's son, not Hoho.
Factors pointing to this, other then the conversations between Lucrecia and Vincent, are all physical.
1) Sephiroth is 6 feet tall. Vincent is 6 feet tall. Hojo the hobo is a small mofo. Considering that height is mostly determined by parental genes, seems odd if Hobo is the father.
2) Sephiroth and Vincent look exactly the same, minus the eyes (mako and chaos) and the hair (jenova). Are we to believe that Square Enix was sooooo cheap that they decided to use the same face for characters who are supposedly unrelated? So cheap that they decided to use the same brow shape, eye shape, nose shape and lip shape...yet Sephiroth is not Vincent's son but Hojo's?
Last but most important and definitely not least.
3) Lucrecia and Hojo both have straight hairlines. Meaning they carry the recessive ww gene and therefore can NEVER spawn a child with a widow's peak. Square Enix cleverly mask Vincent's widow's peak with a bandanna or bangs (when he was with the Turks), but Doctor Grimore Valentine, Vincent's father, sports a widow's peak in his brief appearance in DoC. Coincidence? I think not.
Sephiroth's two fathers in denile:
Vincent (to Lucrecia): But using your (not assuming responsibility, vinny?) own child for an experiment?
Hojo (interrupting) : I don't know what you're implying...blah blah blah...YOU are the LAST person to have any word in this. Now leave us at once, boy!(more like the one of the first person to have a word in this!)
Lucrecia: But what? If you have something to say, say it.
Vincent: Are you... Are you sure this is what you really want?
Lucrecia: Am I sure? Am I sure!? IF THIS ONLY CONCERNS ME, then yes, I am sure! (what a nice way to say man up to your child)