It doesn't matter if it is a straight or gay wedding, the question of children at weddings can often be fraught with problems. If you decide that you do not wish to have children attending then you must make this clear on your wedding invitation. Although heaven knows what the hetties will think when they receive an invitation with Adults only on it. You may have to compromise where a brother or sisters children are concerned.
If you are happy for children to attend, then provision must be made for them as young children do not have the attention span to sit through an entire service. At the actual ceremony venue, ask if there is a room where a parent can sit with a child if it is crying to prevent too much disruption.
At your reception venue, make a table specially for the children where you can put colouring books, pencils, paper and puzzles or anything else to keep the little dears entertained during the reception.
Try not to site the table near an exit and either hire a nanny, check with your wedding venue if they can supply one or get a parent to supervise, you don't want to loose any of them do you? Yes children at weddings bring their own problems and needs.