This is my first EVER baby chick fest. I have 3 BR & 2 BO. They are 7 days old. All are growing fast but 1 of the BO is not developing tail feathers. All of the others are. Is this normal? Could that be a sign of gender? She is growing and seems happy. Always the first one to check us out when we check on them. Thanks for any info. Semi-worried baby chick momma.