Its heavily implied that Laguna is Squall's father,
(SPOILER)Laguna married Raine, Raine got pregnant, Raine had Squall, Raine died while Laguna was away, Squall and Ellone were taken to the orphanage.
its been a lonnng time since i played 8 but i always thought it was pretty clear.

Lulu's baby Aurons? then how come its got red hair lol. that kid is definately Wakka's.....or Reno's?

either way its a differnt world where different rules apply, because one day Yuffie will be older (physically) than Vincent, so would anyone he tried to go out with, so wots he sposed to do, just be a moody sob for eternity?