In your new life, you are not alone. Most, if not all, of your family members have also reincarnated to become your family members. While they may or may not have a build, they have been reincarnated to be a part of your new family. Your new family is now your old family, even your beloved pets. If your new family does not have enough members to fit your old family, the new family will be expanded to fit them.
If there are certain members in your family you do not want to be reincarnated, you can choose not to bring them along. You can also choose to bring your extended family if you choose to.