Really You are never to old to adopt, or do anything.
18 & Up
18 if you have no criminal record. so be good. The age when one is eligible to adopt a child is determined by the state law in which the potential adopter lives. However, there are a multitude of...
Depends on where you live. Some allow from 18 and others not until you are 25. If you are related to the child that can also play a role.
No. You must be an adult, eighteen or over, in order to legally adopt.