Bofoi created a Cyborg which malfunctioned and killed Genos' parents, Genos was saved by someone else(probably Drive Knight) and Kuseo restored him.

Genos was suffering from some disease and had to become a Cyborg, Kuseno operated on him but he malfunctioned and then went on a rampage, though Dr. Kuseno later calmed him and implanted false memories so that Genos won't feel guilty. Drive Knight's caution was just a well wisher's warning about Bofoi.

The Cyborg who destroyed Genos' town was someone else, though in past Bofoi experimented on a different Cyborg and that's why Drive Knight cautioned Genos about Bofoi.