Lately, I’ve been curious about genetics and what gets passed on to children.
Is either a large chin or small chin a dominant genetic trait (autosomal)?
If not, is it polygenic?
Hypothetically, if a man with a large chin doesn’t want to pass that feature to his children would it benefit to mate with a woman with a recessed chin? Would it result in something in the middle? I am sure it is not a guarantee but does increase his percentages of not passing it on.
Thanks…
Is there some kind of professional or paid service that could answer these types of question?
My 99% certain WAG is that there’s no simple genetic determinant of chin size. It’ll almost certainly be some complex mixture of polygenic inheritance and non-genetic developmental factors. Most physical traits aren’t very simple.
There are genetic counselors that advise people on similar questions, though they mostly focus on genetic diseases, their consequences, and the likelihood of a couple passing it on to their children.
Jay Leno may know.
Very few gross anatomical features like this are going to be down to an easily understood combination of a few genes, simply because it’s going to take so many things working in concert to generate them. That intermediate area between the molecular effectors of development and physical features that we see and notice still isn’t very well understood, though of course there are a lot of very smart people working on it. It’s going to be a whole host of factors that contribute to general facial shape, and since every person’s face is different, it’d be a monstrously difficult problem to tease out.
Add to that that “big chin” is a very vague description from a scientific point of view.
My mother has pretty severe TMJ disorder. The oral surgeon has said that jaw shape and the malalignment of teeth and jaw is heritable.
I have much milder TMJ symptoms than my mother. I had major orthodontic work in my teens for realignment of teeth and my bite. I also had a sliding genioplasty to correct a receding chin (which is a common facial feature in my family).
Post-surgery, I have found that my bite and alignment is much better than it was pre-surgery. Apparently, where my mentalis muscle and the mental protuberance were situated, my surgeon wasn’t surprised I was able to actually close my mouth comfortably.
If he doesn’t, Bob Remus, AKA Super Destroyer Mark II, AKA Sgt. Slaughter would probably know.
Generally I suspect you’re correct, but there do seem to be some partial exceptions, as with mandibular prognathism, i.e. the famed “Hapsburg Chin” ( though even that heritable trait seems fairly complex ).
One of the factors in chin size is gender rather than genome. Male facial bones grow disproportionately larger than a female’s facial bones would if both genders have the same genes present. This is a direct effect of male hormones.
(And this is why I have a harder time recognizing my former male students than the females…male faces change a lot more between the teens and adulthood than female faces change. At least that’s what I tell my wife…)
Do any of your brother and sisters have the same thing? Moreover, do your kids have a recessed chin?
My sister has the recessed chin. She also had extensive orthodontic work as a teen and does not suffer with TMJ disorder.
Neither of us have children.
As an aside, the treatment used for my mother’s TMJ probably contributed more to how hard of a time she has had than anything else. She did not have orthodontic treatments until she was well into her 40’s, but her TMJ treatments starting when she was in her 20’s. When she started treatment, surgery was the standard using metal or silicone implants. Her body rejected the silicone, so they rebuilt the joint using her own tissue. That failed and she had partial joint replacement with a metal implant. The metal wore away the bone it was scraping against and she had to have complete joint replacement (done by only two surgeons in the US). Luckily, I happen to work with one of the surgeons that does the procedure and due to her extensive history, she qualified for the surgery. Nowadays, surgery is the absolute last resort for TMJ disorder. They attempt to correct bite and malalignment and the other causes before cutting.