Well, not THAT easy a question. At hatching, it can sometimes be very difficult to determine what color a snake will be at adulthood. Yes, it is easy to tell a normal from an amel, but not as easy to tell how the normal will look as an adult, or even the amel. You can get a fairly good idea by what the parents look like, by comparing siblings, and by experience. But sometimes, you really don't know until it happens.
I've had certain snakes "change" color during their first 6 months, then even more over the next 2 years. IMO, you have a pretty good idea as to what the snake's final coloration will be when it is 2-3 yrs old.
A good example of how a snake can change:
This anery A motley/stripe is about 6 months old in this pic. At hatching, he was basically solid black pattern on light grey.