Is metastatic squamous cell carcinoma genetic?

Genetic component? There could be genetic component to a squamous cell cancer, although the exact implications on treatment aren't known. Obviously if there is a strong family history of cancers, or if it strikes someone who is young and/or a non smoker/drinker i would suspect a strong genetic contribution. Without more details, it is hard to say with any certainty.
No. Generally no. Usually environmental -- such as tobacco and scc lung cancer for instance.