Definitely born, and I think anyone who thinks made hasn't experienced a TRULY fussy eater.
I have two extremes in my children - ds eats a HIGHLY restrictive diet and dd will eat anything that is put in front of her. Ds at 4.10 has just started eating fish fingers, cold sausages and shepherds pie. Before this he would ONLY eat cereal, bread, occasionally cheese, milk, peas and pasta. He won't eat yoghurt, or petit filous, is tremendously fussy about what biscuits/chocolate he eats (and I don't tend to give them to him anyway because I don't want him filling up on these). He will occasionally eat fruit now, and is getting much better about things like mashed potato. Won't eat any sort of egg or anything like that.
Dd will literally eat anything. She loves curry, asparagus, salad, all types of meat, devours fruit. I have done nothing different with her to with ds.
I've come up with a couple of reasons for why they're so different.
i) Robert Winston talked about 'super tasters' and I think ds may taste things really strongly (like hunker said about tastebuds) - if I hide something, say in shepherds pie, he says 'it smells horrid' and won't eat it - e.g. pureed cauliflower in the potato on the top. He often complains about the 'smell' of something and sometimes has to sit at the other end of the table if we are eating bolognese sauce or something so he 'can't smell it'. Dd has been known to eat green chillis without blinking, so I think children MUST taste things at different strengths.
ii) he finds textures difficult, and although he has been known to try meat, it either makes him gag and be sick (and as a newborn he was a very fussy 'eater' - was a nightmare to b/feed, and was frequently very sick) or he will keep it in his mouth for up to 2 hours, unable to swallow it.
iii) ds is much more 'hyper' than dd - she has very good concentration and will sit and finish her meal. Ds wants to be 'on with the next thing' and as soon as the edge is off his appetite he's off. We are strict about leaving the table, and he doesn't come back, but he will eat a few mouthfuls of something he likes and then go.
Reading this back, it's very long (sorry) and doesn't reflect that ds is loads better than he was, within a restrictive diet - he is expanding his diet slowly. He also gets quite anxious about things, so we have been careful not to make meals an anxious time, but I don't see that we could have done anything different. I know people say 'no child will starve themselves' but I think ds would - he is naturally thin and has had periods of near emaciation, because he doesn't recognise the 'hunger' signs - like dh he just gets really grumpy and then doesn't want to eat, because he is too grumpy.
So I would say born!