Thanks for all the input! The only cat we saw hanging around that we believed to be the father was a black and grey tabby with big round eyes and a smushed face.
Also, the calico and gray (diluted calico tabby?) are girls, tan and orange are boys.
The gray kitten has tan patches and faint tabby stripes throughout her body
Black calico has mottled tortoise shell like fur on her trunk but orange striped legs:
I'm a college student in Philadelphia. My roommates and I decided to bring in a stray that would hang out by our back door once we realized she was pregnant. Here is mama:
And here are the 4 kittens. These photos are all different ages
They all have similar faces except the gray one...