Wrong.
The casting process results in greater control of the net shape in the forming process, which is evident from visual clues in the finished crankshaft. Looking at the counterweights is a dead giveaway. A forged crank's counterweights (left) will generally have a rougher look with rounded edges, while a cast crank (right) by comparison will show sharp, well-defined edges.
A second visual check can be made by viewing the parting line that defines where the casting core or forging dies separated. A cast crank will have a thin, sharp, and straight parting line (left), while the parting line on a forging will be wide and generally less defined (right).
For the visually challenged, a forged crank can be identified by ear. A forging will ring like a bell when tapped on the counterweight with a steel hammer, while a casting will give a dull thud.