@Jude – it may be helpful to decide what you actually mean by a ‘talent’ for art. There are some interesting answers here, but I tend to disagree with @wundayatta about talent ‘being earned’, and to agree more with @lucillelucillelucille that doing what you love and getting any compliment at all is fine.
Certainly an aptitude for creativity is a likely prerequisite for good quality work. If a child shows a natural tendency to be resourceful, to have ideas and to make good use of materials provided for play, they may well develop talents, if they have an interest. The question is deeply subjective though. Success as an artist is not entirely dependent on ‘talent’, especially these days; business acumen and an eye for popular culture are at least as important.
To find out for oneself, to see if one really is ‘talented’, requires the learning of discernment; developing an understanding aesthetics and actively producing stuff. Then showing it to people, preferably in the same field. There are accepted means by which we judge how art is good or not. The most difficult bit is seeing one’s own work against others and comparing, as objectively as possible. It doesn’t help to be precious about it. The purpose of one’s exploration is important: if you just want to make good work, for enjoyment, take a few classes and enjoy. If you want to sell work in a specific market, then research the market and go for it. That way, you might make some money.
If you want the Saatchi gallery to buy your work, or any major art gallery, then you have to be seen – exhibited – in the right places. Again, ‘raw talent’ is not entirely necessary.
Personally, if you can draw from observation and produce likenesses, it shows you can see what is around you. This is fundamental to painting and sculpture. Draw like a demon, practice as much as you can, put energy into the work, give the images life. When you look at something you have done a while ago and you think someone else must have done it, maybe you do have talent!
I always write loads for art answers! Good luck anyway lol