It would depend on the original plant's history (where the seed came from). If you got a seed from a plant that has been "stabilized," than you should receive similar results from each seed. But if the plant you have is a relatively new cross, then your chances go down. Keep in mind that every genetic had to come from somewhere, most plants on the market as sold by reputable vendors, should be stable and should produce the same or very similar genetics.
If you ever want to wrap your mind over a fun topic, do some searching on the net for cross breeding and back-crossing. A lot of times a desired genetic will be created and basically inbred to keep the genetics stable. This is a VERY basic view of what breeding entails, but it is very interesting.
And it does not work with every type of plant. For an example, citrus plants are not bred like this. That is why, if you notice, when you buy a citrus tree from a nursery they are all grafted. For citrus, if you plant a seed, you are basically rolling the lottery. You can get just about any combination of genetic from almost all the way back to the orinigal genetics of the tree and everything in between. In-other-words, the seedling from a citrus seed could be anything from better-than-the-original to not fruiting at all.