In human anatomy, Chin is the lowermost part of the face. It is formed by the lower front of mandible. Then when it appeared an indentation (or also referred to as a dimple) in the center or tip of chin, then termed a Cleft Chin. There is also a call with a less polite term, that is a butt chin. And there is a 100% chance that a child will have a cleft chin when both parents are visible carriers of the gene.
Cleft chin is actually genetically determined and is caused by failure of the lower jawbone to completely fuse together at the center point. This doesn’t cause problems for most people with a cleft chin; it merely causes variance in appearance (learn more about what is a cleft chin on Wise Geek). Wherefore, cleft chin is clearly a smallness thing, then the nature of Cleft Chin is unique or cute.
Then take a look at Sandra Bullock's face below, although not very visible, it turns out, Sandra Bullock has a facial cleft chin. That is, behind her face that can be said quite proportional, She has the cuteness charm, because of its uniqueness. In physiognomy, a cleft in a chin shows someone who is self-centered and with a hidden agenda.
Perhaps the image here does not show clearly Sandra Bullock's cleft chin, click on this picture which shows that Sandra Bullock is a cleft-chinned woman. In addition to her typical wide smile, now Sandra Bullock has another characteristic on her facial beauty.