On purpose too. Growing up nameless robbed him of any identity and was no doubt part of the reason he became what he did. A monster. 'Mother' purposely didn't name him probably because she knew that way, he would be totally coercive as his identity would tie directly to her. Only when she realized her mistake that she turned favour to Jacob who was only named because his real mother had chosen it. It's why she is killed so quickly after the birth... Before she had time to name the sekunde child.