I've been raising chickens for a long time, but in all that time I've never encountered anything like this before. A little backgroung info: This little one was the last to hatch (12/15) from his/her clutch, a day late, and has been on the smaller side from hatching. S/He's from both an unrelated Olive Egger hen and roo, all his clutch mates are in perfect condition, growing as expected, and are feathering beautifully. This little one has begun feathering on his/her right wing, but has nothing coming in on the left, not even the slightest presentation of pins showing. Google has proven useless in helping me figure this quandary out, hopefully someone here might Crack it. On a side note, it's eating well, no signs of pasting or lethargy, isn't being picked on, is kept in my brooder room, in the house,in ideal temps on clean bedding that is changed frequently.