In the year 2030, the growing Villain population surpassed that of Heroes, the need for vigilantes was most dire , as the new Heroes haven’t appeared nearly as fast as the Villains did.

The solution proposed to the UN by the S-Labs was simple, to create an artificial heroes that would be deemed strong enough to be sent out to neutralize or annihilate any form of Villainous uprising  at whim - Homunculi.

Using hardware salvaged from one of the alien incursions apprehended by government sanctioned Heroes, the serum for Homunculi creation was made.

The experiments were a success, with varying results depending on the test subject and dosage of serum used, each resulted in varying form, intelligence and ability. 

To maintain close eye on the subjects during their operations the TAG system was made, a simple ear clip which contains tracking device, multiple biological scanners to constantly check the status of the Homunculi,and a communication link .

I think that about explains about Homunculi origin in general.

Apologies for terribad grammar , writing is not my strongest side.