Can donor hair for FUE be from someone else (child or sibling)?

You cannot harvest donor hair from family members.  The only exception would be a genetically identical twin.

No, unfortunately the donor hair cannot be from another person, even a close relative. The tissue will be rejected in the same way that a transplanted organ is rejected. Work with a skilled hair transplant surgeon to determine all of your options regarding hair transplant and different donor site techniques. Best of luck!

The patients hair being transplanted must be from the patient themselves. If you are concerned about not having enough hair to donate into the desired area, a qualified and experienced hair transplant surgeon can take grafts from the chest, underarms, and even the groin area if there isn't enough donor hair on the head. If you are interested in FUE, find a highly experienced, qualified hair transplant surgeon who specializes in hair transplant surgery in the US and schedule a consultation to determine whether you are a good candidate . 

Unfortunately the hair needs to come from your own scalp. Chest and back hair have been transplanted as alternatives although the process is quite involved it remains an option.
I hope that helps!

Jeffrey Watson, M.D.
Hair Restoration Specialist at Moradi MD
Graduate, Harvard Medical School

No- hair transplants must be genetically identical. So, yourself or perhaps an identical twin, if they have hair to spare for you.

Hair that is transplanted from one person to another would be rejected by the recipient’s body and would lead to many complications. Even if the patient were to take anti-rejection medication for the rest of their life, it would still have a fair share of complications. It might be possible to take the donor hair and use it for a transplant if it were transplanted between identical twins who have the exact same genetic makeup, but even that is just a theory and has never actually been tested. The risk of side effects from the medications that would be necessary to counteract the numerous risks of transplanted hair from another person far outweighs the benefits of trying it. Scientists, however, are currently researching possible ways for the donor hair of one person to be used as transplanted hairs in a different person without the hairs being rejected. These researchers are also working on a way to be able to take a single follicle and multiply it in a petri dish. Personally, I will wait for a while before practicing this method to make sure that all of the results of the tests are good and everything is safe.

The donor hair must be from yourself of an identical twin. Cross over to other people will cause rejection of the hair just like a kidney