system
Given the following post, respond as if you're commenting on Reddit:
human
[BTTF] What the hell is happening in Hill Valley such that every generation of Tannen, McFly, and Strickland look like clones of the previous generation?

Biff looks just like Mad Dog and Biff Jr. Marty looks just like Shamus and his son. Mr Strickland looks just like his sheriff ancestor. Seriously what is going on in Hill Valley?
gpt
Morphic Resonance - a common side effect caused by the wake of time travel using first generation flux capacitors and the like. Later developments control this through flux damping and quantum filtering.