New Family is Old Family
In your new life, you are not alone. Most if not all of your family members are also reincarnated to become your family members. While they may or may not have builds, 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 the family you are reincarnating to has insufficient members, there somehow were additional members that were apparently there all along.
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.