How Could We Have Been So Wrong?

So, we got our chickens from a local elementary school - a kindergarten class to be exact.  The kids had hatched the eggs with an incubator and as the chicks grew, their teacher was anxious to be rid of them.  Lucky for us because we were looking for chickens at the same time, so were able to obtain 8 babies that were around 7 weeks old at the time.  One of them, an obvious roo, was killed by a dog unfortunately.  We figured our cochin was a roo too as his comb and wattles came in quickly.  The others we chalked up as hens.  
The cochin was the first to make me wonder.  His feathering and body was filling in like a hen's, and the vibrant comb and wattles really weren't growing much anymore at all.  He is very docile, although quite large...the largest of the flock actually.  I'm not convinced anymore that he is actually a he...I hope if he turns out to be a she, she won't mind the name Arthur...;)

Last week, I also started getting suspicious over our toddler's chick, Brownie.  Her tail feathers were getting suspiciously long all of a sudden and she was getting some really vibrant green feathers as well.  My suspicions were confirmed yesterday morning, when a very definite cock-a-doodle-doo was heard loud and clear.  I peeked outside as they were already out running around, and sure enough, there was Brownie standing tall and welcoming the morning as only a rooster can do.  How could we have been so wrong?  I must have missed some obvious signs.  Our older daughter's chick is now seeming suspicious to me as well.  I'm starting to see a couple curls on the tail feathers.  Her name is Tree, however we may have been wrong about her being a her as well...time will tell!

One thing I know, if we end up with 2 roosters out of this bunch, I will be getting some more hens....:)