Because Ireland is not a part of the Schengen Agreement - all EU citizens entering Ireland will be required to present a passport or a valid national identity card.
Family members who are not Union citizens
Non-EU family members of EU citizens who are in possession of a residence card
and are travelling with or to join EU family members can enter Ireland on presentation of their passport and a valid residence card, including a permanent residence card.
Documents for minors
Other than their own valid travel document (passport or ID card), no particular official authorisation is required for minors of any EU country to enter or leave Ireland.
However, it is advised that anyone under the age of 18 who is not in the care or company of an adult, presents the following documentation:
a signed letter from the child’s parent(s)/guardian giving consent for travel and providing his/her contact details
a copy of a document identifying the parent/guardian, e.g. a copy of the picture page of a passport or driving licence
evidence of the parent/guardian relationship with the child, e.g. a copy of a birth or adoption certificate, or guardianship papers
a death certificate in the case of a deceased parent
If the minor is not ordinarily resident in Ireland:
full address of where they will be staying
full contact details of who they will be staying with