Can you adopt your nephew?

Contact an international adoption agency that specializes in his home country. You can find more info on international adoption at adoption.state.gov Best of luck!

You can adopt someone to be your child but to be your nephew he had to be adopted by your siblings. Then he will be your nephew. There is no nephew-adoption.

This depends on the legalities of the area you live in as well as the wishes of the mother/family.

Your nephew is no longer a minor and quite capable of looking after himself. He's considered an adult now so the normal adoption process that would be used for a minor doesn't apply here. However, if...

I assume your nephew is a minor. If you live in the United States and he is not a citizen of the United States, there is a procedure you can use to make him a citizen. There are immigration lawyers...