The dog is still very young and he's still learning. He is not going to just stop one day. It takes weeks, most likely months. He is learning to be a dog living with humans. If he were in a natural setting with other dogs, it wouldn't be a big deal. You are teaching him not only not to bite, but how to live as a house pet. There will be easier things that take even longer and all of those things will take years to do consistently and with distractions. This biting thing will be over in a couple months and there will be something else which will probably take even longer to train out of him. It's a part of raising a puppy to be a well behaved adult, which you can expect around the age of three.
As consistent as you and your family are being, there's a pretty big chance that everyone is doing things a little different, and dogs pick up on those differences. I know how hard it is for kids to not get a pup riled or want to play with hands (it happens with the best of them). Because of the small, and maybe some large, nuances between you and the three or four other members of your family, the pup may take a little longer to learn, also. It happens with adult couples as well.
For comparison's sake, a friend got her pup the same time as you and he is the same age. I have seen him every weekend (three times) since she got him. He is in puppy class, otherwise, she is in a similar situation (a spouse and two teenagers -- she's also never had a puppy). Her pup is still biting and going after clothes, though he is getting better in that he does it and then you correct him and he stops. Instead of waiting for him to go back at it, we do something to redirect him, like rolling a ball. A lot of people will just stand there and wait for the puppy to do it again so they can keep correcting him. That's like having a stand-off with a two year old child.