The Brian Kennedy story is true. So it the fact that Eddie Irvine is the father of Yvonne's child. The pressure was on Ronan to dispel rumours about his sexuality was so great that the pair entered into a marriage of convenience and pretended to have had the child together.
While I'm here, Katies Holmes (Tom Cruise's wife) was pregnant by her former boyfriend when she met Cruise. Again under pressure to prove he wasn't gay (all his children up to this point had been adpoted) Cruise got hitched with the then pregnant Katie and passed the child off as his own.
Not sure if anyone remembers that nobody was allowed to see Katie's kid for the first four months - the reason was she had it three months before and she wore a prosthetic bump to keep the illusion up. Cruise to this point still has no natural children from three wives.
You're probably asking why would someone marry Tom Cruise if he was gay. Well they get guaranteed roles in movies and quite often more. Nicole Kidman got an Oscar, so did Penelope Cruz (ex girlfriend) just around the time she was threatening to go public about their relationship. Katie Homes will get plenty of parts so long as she stays with him.
I'm not making any of this up, I work in an industry where this stuff is far beyond rumour, it's simply fact.