So, i started Porterhouse F1 for the first time. And now that they are getting their mature leaves, I noticed one of them have Potato Leaves! I was extra careful with the seeds, and only had one pack open at a time. And each cup was prepped as the next packet was open. So there wouldn't be any seeds dropping into a nearby cup of dirt, because there wasn't any.

So, I'm very certain that these are either one of the parents, or a mix up during seed distribution.

Does anyone know the parents of the Porterhouse F1?

I don't know about its lineage.

Here are the likely possibilities I see (which are mostly like the ones you've mentioned):
* The PL plant is stable, and it's the matriarchal parent of the cross. I would totally grow it, considering this possibility.
* The vendor got a stray seed of another variety in there.
* Maybe they sold you F2 seeds instead of F1. (I consider that false advertising, unless they actually say it's F2 seed, and ideally warn you of the difference. If they're a reputable seller, I wouldn't suspect this.)