True, it's been stated that Sabertooth is not Kyle's father, but in other titles it's been hinted that he is, "Changing Writers Syndrome"...
In Marvel Comics Presents #51 Wolverine said he knew Kyle's "Old man", and that he'd (Kyle's Father) learned to control his bestial tendancies, though he didn't give a name. It's possible he was referring to Wyre, who is, in a sense, Wildchild's "father", but Wolvie's never mentioned Wyre anywhere, he may not even know him.
I think whoever took over Kyle after Alpha was leading him towards being Creed's son, especially in "The Wilding" story arc in MCP #51-53 (Rob Lifeld wrote that one), but they decided against it somewhere during X-Factor, leaving loose ends strung all around the MU...
We wrote about this for a while in one of the other messages, I can't remember which...