Do you really have to be certified to do a tattoo ?

my friend and i knows this quy that does tattoos really qood . his needles are clean and everyone talks about how qood he is at school . do you REALLY ave to be certified to do tattoos if you know how to do them ? * even if the needles are clean and sterilized . my friend's mom won't let her qet it if he's not . please let me know . thanks :)