I think my ex-stepmother is unfit to take care of my two-year-old sister. How old do you have to be to adopt a child?:confused:

Are you able to support the child financially? Can you put a roof over your head, feed, cloth, transport the child to the doctor if required, etc?

You need to be old enough to be able to support yourself and a child without any kind of state help.

You also need to be at LEAST 18, though some states have higher age restrictions.

If you don't feel that your stepmother is fit, then you need to call CPS and get them involved before the child is injured.

You need to be at least 18. However you also need to be stable, both financially and emotionally. Its unlikely a court would allow a young person to adopt a child unless there really was no other option. Unfortunately, age does play a part in the adoption proceedings no matter what anyone says.
The thing is, unless you can prove that your step mother is unfit, and actually provide proof, CPS won't do anything. If you file a complaint, they'll investigate. If they find she is unfit, they'll remove her and place her in a foster home. You'll need to let CPS know of your request to adopt, however it is completely up to them, and the judge whether you'll be able to or not. Its all based on your lifestyle, and stability (and age).