As recently noted by Slate Magazine http://www.slate.com/id/2232409/ and in turn commented on by Steve Sailer http://isteve.blogspot.com/, facial characteristics may provide clues to the personality of the man behind the face. Specifically, the effects that prenatal testosterone exposure has on men include giving them more or less masculine faces, and leaving them with more or less aggressive personalities. The various descriptions for masculine faces include a strong square jaw, a pronounced brow, small eyes, and a wide face. Another indicator is the ratio between a man's index finger and his ring finger - the shorter the index finger is in comparison, the more testosterone exposure. Prenatal testosterone, in addition to shaping a man's face and fingers, shapes his brain.
So what does this mean in an employment context? It means that employers may be able to tell more about potential and current employees by their faces than they thought they could. Certain jobs might favor masculinized brains, in other positions, such brains may be too hot-headed. An employer might look hard at the face of his top performers, and try to duplicate those facial characteristics in otherwise qualified employees. Some sales positions call for aggressiveness and lack of patience, which would be ideal spots for more masculine brains. Other positions call for empathy and require patience, for instance project or collaborative work, for which an over-masculine brain would be illsuited.
But is that legal? Obviously, one problem with such a selection is that these facial markers are going to vary greatly between the sexes, and even between racial groups. A judge would laugh at the suggestion that facial characteristics are bonafide occupational qualifications. Even between candidates of the same sex and gender, such selection could be termed "gender stereotyping", or may run afoul of state laws that can protect homosexuals or those perceived as homosexuals.