Translation:My children are already young consumers.
In this case if it would mean "all" it would have been "Mijn kinderen zijn allemaal jonge consumenten".
It's a different word type:
- alle grote kinderen = all big children
- ik ben er al = I'm already here
- Ik ben er al = I'm here already
- Al is hij groot, hij is niet de grootste = Even if he is tall/big/great, he isn't the tallest/biggest/greatest
These all have the same meaning:
- Al mijn vrienden = All my friends
- Alle boter is op = All butter is used up
- Ik ken alle nummers van de Golden Earring = I know all songs by the Golden Earring
- alles = everything
Aller is a remnant of a case system that used to exist in Dutch, it's only used in fixed expressions like de beste aller tijden (the best of all times). Similar to the second group above, and you can change it to de beste van alle tijden which has the same meaning.