I could make this longer.  But I won't.

Cat showed up one night.  Very friendly, almost over the top friendly to humans.  
Same cat didn't like our other cats.

Cat had kittens.  Kittens were over the top friendly to humans.

Mom cat killed when kittens were 6 weeks old.  We raised kittens.  2 of them killed on highway and one left.

The little female that's still with us after over a year follows me around.  If I walk out the door and she's out in the field she comes running at top speed.  When I work in the shop at the router or table saw she watches from not too far away.  If I have everything shut off and am measuring or adjusting something she's there. 

When I go back to the house she runs ahead of me and jumps up on the bench waiting to be petted.

I've never had a cat that acted like this nor have I seen anybody else have one like this.  She's more like a dog than a cat.

So I wondered is there a breed of cats that have this trait?  Her mother and brothers were similar.