Some of the rumours about Ryanair are true, and some are not.
They hire (and still do) people from all over Europe, regardless of the country they're from, and this does include Irish. I don't know the point of starting a fake rumour but I can tell you for sure that this one is purely fictitious.
However, they do hire mostly pilots under 30. I know some who've been hired at 32, even 37, but most are under 30 when they join Ryanair as a cadet pilot.
There are a lot less female pilots than in other airlines, and for some reasons most of the female pilots are Captains and not FOs.
Also, they seem to prefer pilots with first time or at least first serie passes on their CPL and IR.