Reproduction
Transformers have been shown to reproduce in a number of ways.
Some are built from scratch and when finished and turned on just spring to life (G1 Catoon Dinobots and Technobots).
In other stories they must be infused with life from an outside source. In the G1 Cartoon this was Vector Sigma, in the Marvel Comic it was the Creation Matrix.
The Transformers: Generation 2 comic introduced the concept of "buding" where it was revealed early TFs reproduced Asexualy until they reached the population Primus desired and then stopped and all memory of it was erased. When the Decepticon Empire rediscovered and revived the process the resulting robots were increasingly less sentient and the lifeform called The Swarm was created as a byproduct.