When they first encountered the Borg kids aboard the cube, the three younger ones: Mezoti, Azan, and Rebi still had hair when they'd emerged from the maturation chamber. The older two were typical Borg bald. It was never addressed as to why the younger ones still had hair.
I speculate that the in-show reason would be that hair loss would be one of the last things to happen before full assimilation in a maturation chamber, thus they still had hair because they'd been released prematurely.
For the real life reason, either the show didn't want to make head pieces for the kids, or the parents of the actors didn't want them wearing them.
I speculate that the in-show reason would be that hair loss would be one of the last things to happen before full assimilation in a maturation chamber, thus they still had hair because they'd been released prematurely.
For the real life reason, either the show didn't want to make head pieces for the kids, or the parents of the actors didn't want them wearing them.