I have two sets of ex-ferals.
The first was a family of four I caught when they were about eight to nine weeks old. One of the four was killed in the 2007 pet food poisoning, the other three, Allen, Rachel and Meghan, are now four and a half years old. They show zero indications of their feral origins and, in fact, very seldom startle at anything. Rachel routinely greets my guests, whether she's met them before or not.
The second family of four, I trapped when they were about twelve weeks old. Those kittens were much, MUCH harder to socialize, even though I pulled a futon mattress onto the floor and slept in the kitten room for three or four months to help them realize I was harmless.
I kept two of those four kittens. Spencer and Heather are now two and a half years old. They both startle extremely quickly, and they both take off for dark, hidden spaces at little provocation. Neither of them will let guests get anywhere near them, on the very rare occasions guests stay long enough for the two to come out of hiding.
Heather is not and will likely never be a lap cat, nor does she like to be picked up. I think, however, that's more her personality than her background. She's very fast, very energetic and loves to run and climb things; she's almost constantly on the move. She sleeps on my bed every night, though, raises her head to me and purrs as soon as I reach towards her, and she'll often cross between my computer screen and keyboard so I'll pet her. I think Heather is perfectly comfortable and is just not a lap cat.
Spencer, on the other hand, still has some progress to make, although we've had a couple of breakthrough moments lately. He clearly wants to be in my lap, but he's having a tough time trusting that it's ok. Twice in the last week, he's settled down to purring on me with his eyes closed, but he still can't bring himself to actually walk onto my lap... he just keeps crossing in front of my face while I'm on the computer, sometimes stepping towards my lap and then drawing back.... over and over until I pick him up and put him there.
I make a concerted effort, every day, to pay special attention to Heather and Spencer (a little more so, Spencer) to ensure they are as social as possible. I think another year will see them lose the last few feral traces they still carry.
I have a sixth cat names Ralph who is three and a half (interestingly enough, all six cats seem to have been born in the September / October time frame). I don't believe Ralph was ever feral, but he has definitely been abused. When my daughter found him, he'd been stuffed in a crate and left in an empty apartment to starve to death (and according to the vet, was about 24 hours away from doing so).
Ralph was the most astonishingly aggressive cat I've ever seen when he arrived here. He would literally lunge across a room to attack my guests, especially women. And he attacked to maim or kill. He once got loose in the apartment hallway and attacked my upstairs neighbor when she came home. I had to leave work early when I received her call - Ralph was refusing to let her pass. He had nailed her pretty good on her hand and arm but, thankfully, she's a cat person herself and totally understood.
I've had Ralph a year this month. He has blossomed into an amazing cat. He fears NOTHING - and I'm totally not exaggerating. He greets every single person who walks in my front door; if they're men, he demands they greet him back, to the point he'll climb whatever he has to to put himself nose-to-nose with them.
He's still a bit iffy with women. Although he'll always let them in, sometimes he greets them as exuberantly as the men, and sometimes it's with growls and raised fur.
On the flip side, he's so laid back and confident, he actively plays with my three-year-old granddaughter. They chase each other around the house, and whenever he catches any part of her, he is ever so gentle - he'll grab with mouth and paws, but there are no teeth or claws involve. It's amazing to watch them.
Hmmm, this post turned into a book, didn't it?!