A chin cleft, also known as a butt chin, is a genetic trait caused by incomplete fusion of the lower jaw bone. It can be passed down from parents to children, but variable penetrance and modifier genes can affect its expression. The trait has existed for thousands of years and is often seen in literature and popular culture.
A chin cleft is also called a cleft in the chin, a chin cleft, or even less elegantly termed a butt chin. It is a small to large indentation in the chin that is actually genetically determined and is caused by the inability of the lower jaw bone to fully fuse together at the midpoint. This doesn’t cause problems for most people with cleft chins; it simply causes a change in appearance. You will often see that parents with cleft chins tend to produce children with the same sign. Parents with cleft chins may or may not pass the trait on to their children, and some children will be born with cleft chins to parents without the trait.
The chin cleft is an interesting study and an example of how genetics can work and how inherited genes sometimes fail to express themselves. In theory, parents who both have cleft chins would pass it on to their children immediately, as it is a dominant trait. There are two reasons why this might not occur, because the genes that dictate clefting can be affected by variable penetrance. Variable penetrance means that even a dominant trait may not be expressed. This can be caused by the environment: something in the fetal environment has caused the jaw to fuse completely. It can also be caused by something called modifier genes, which affect the function of the genes responsible for the chin cleft.
If the modifier genes suppress the gene that controls incomplete fusion of the jaw, then the cleft would not be expressed. Alternatively, two parents without cleft chins could both have had modifier genes, resulting in fusion of the jaw. Their children may not have these modifiers and all have fissures despite this. The point is, whether or not parents have clefts, children may or may not have them. Variable penetrance can cause some confusion, but it explains why clefts aren’t always inherited, or can appear among children whose parents don’t have clefts, although this is rare.
Cleft minds have certainly existed for a long time. The fossil remains of Homo sapiens discovered in France in the Isturitz caves are carbon-dated to tens of thousands of years old and show prominent fissures. The cleft chin also predominates in the literature.
Villains often have deep fissures, and so do heroes. We also love our current and past actors with split chins, such as Cary Grant, Kirk Douglas, Michael Douglas, John Travolta, Jude Law and Sir Ian McKellen. It should be noted that many of these actors have played both villains and heroes, and the split chin appears to be one of those adaptable facial features that can lend themselves to dramatic expression in different ways.
Protect your devices with Threat Protection by NordVPN
