I had a long discussion with my brother about this a few months ago. His argument was that so long as we manufacture robots, and know that they have some basis in programming that we have a hand in, that he could never come to believe that they are alive like we are. The fundamental argument I believe he was going for was that the randomness of our genes and situation of birth and upbringing, would fundamentally differentiate us from something that we build.
Try to imagine how a company would be able to sell a product where it didn't know what the product would be like at the end of the manufacturing process; a dishwasher that only liked running at 2 in the afternoon or a vacuum that was afraid of floor vents. I've seen dogs that are afraid of floor vents, but would we want something that we see as a tool to have those kinds of quirks?
Even if we were to build a companion robot, whose characteristics could be significantly random, the client would likely want to stipulate what those characteristics would be, and the robot would have to have some kind of slave mentality, lest the client complain to the company that their partner walked out on them and the company was to blame. It's not like they would be pets, where the pound have no control over the characteristics of any particular animal, and so if the pet runs away, the pound can't be held to blame; they had no hand in or control over the pets' characteristics.
In that regard, the future of human engineering is worrisome. If we could pick out traits, not just avoid debilitating disease or sex select, and be able to make someone come out exactly as we want them to be, would that make us any different from a robot? Or would we be 'grandfathered' in as alive?
An idea that has been presented in other fictional media before is the systematic replacement of your brain with synthetic materials that would perform the same function, and make the same connections. Eventually that could be either extracted and put into a brain dead body and rebooted as 'you' or shut down the biological part of your brain and run completely on the synthetic. What if it were done in reverse, so that a synthetic brain were replaced by biological components? Which of these would be alive?