3 week old with strange behavior-- Rooster?

[sunny & the 5 egg layers]

I have a three week old standard chick in with 2 bantam chicks. The 2 bantams are one week older then the standard. The standard has sprouted a pink comb and some wattles too. This morning, I noticed him jumping up in the air and landing on the other chicks backs. Does this behavior mean that my chick is a rooster?
Thank you.

 

[scratch'n'peck]

May be a rooster, but 3 weeks is too soon to tell.

 

[sunny & the 5 egg layers]

May be a rooster, but 3 weeks is too soon to tell.

Even with this aggressive behavior? Thanks for your response, by the way.

 

[PsychedChicken]

Aggressive behavior does not mean a rooster. My most aggressive chicken is a hen.... I'd cull her if she didnt lay so well... But my Roosters are sweet. They dont even fight each other.

 

[RedDrgn]

Any chicken can be, or become aggressive. I don't know what the disparity in sizes between your chicks may be at this point, but keep in mind that pretty much any chicken of any age will go after/pick on any other chicken it thinks is in any way weaker than itself. So you may need to separate your bantams to avoid injury.