Izuku is quirkless. His dada had left him. His dad wrote a lot about alchemy. His dad wasn't able to use it but Izuku had read through the books as much as possible. He read them at least twice a day. He practised it doing it for months. He, unlike his father, was able to use alchemy. His mother died when he was 7 leaving him with the Bakugo's. Izuku spent the next four years practising his alchemy and transmutations. He found out about human transmutation when he was 8 and decided to bring his mother back. It cost him an arm and a leg but it failed. It brought something back just not his mother.