All parents react differently to their children, whether they have one or four children. Some are immediately drugged by them, others may not have this immediate feeling. Both of these reactions are normal. If you are separated from one or more of your children, for example if they are in a neonatal care unit, it may be difficult for you to believe that the children are really yours.
This may make you feel a little distant from them, but try not to worry; when you start taking care of the children yourself, it will start to feel real. In the meantime, show pictures of babies at home and show pictures to friends. To help the bonding process, try to find time to cuddle, chat and get to know each child individually.
Attachment to more multiples can be especially challenging as you will of course have less time with each child, but even 5-10 minutes each day can help you and your children develop a relationship where you can see their individual personalities emerge.