I have heard this is incredibly rare and can only happen if the father is shorter than the mother, otherwise their male child will always be the same height or taller than the mother.
An example would be an adult son who is 5ft 5in and a mother who is 6ft 1in. Could this happen even if the son is healthy?
It’s rare, not impossible.
I mean, the mother could have some hormonal problem leading to excessive height, which she doesn’t pass on to her children. As just one example. Maybe it’s caught early enough so mom doesn’t wind up freakishly tall or with acromegaly, but still taller than you’d expect from her genes for height, so her kids are significantly shorter than she is.
The genes determining height are several - assuming parents are heterozygous for this and the roll of the genetic dice have all the genes going to the son being those on the shorter end rather than the taller you could wind up with a son shorter than his mother.
Arguably, you could say some forms of dwarfism are healthy, in that the person has a normal lifespan and general health even if not normal height so that could happen.
The easiest rule of thumb (in the U.S.) to find the most likely height for a child of parents of a given height is to average the father’s height with the mother’s height and subtract 2.7 inches for a girl and add 2.7 inches for a boy. For the case that you give, you average 5’5’ and 6’1" to get 5’9". The most likely height for the boy will be 5’11.7" for a boy and will be 5’6.3" for a girl. That’s just the most likely height though. I’m not sure what two standard deviations for the heights will be. I suspect it’s about two inches. If that’s true, you can expect the height of a boy to be from 5’9.7" to 6’1.7" about 95% of the time and the height of a girl to be from 5’4.3" to 5.8.3" about 95% of the time.
The reason that I specified that it be in the U.S. is that I know that the average male and female adult heights in the U.S. are 5’9.5" and 5’4.1", so the difference is 5.4", and half of that is 2.7" (in the U.S). In any case, it’s actually expected that a boy will be slightly shorter than his mother if the mother is considerably taller than the father. There most certainly is no rule that the boy will nearly always be taller than his mother. It’s not common, but it’s certainly not incredibly rare. For both boys and girls, one’s height is inherited from both the father and the mother, adjusted by the fact that boys will be taller on average.
The reason I know a lot about this is that I’m male and 4’11". My mother was 4’10" and my father was 5’5’. That makes me somewhat shorter than what’s expected at random but not by a huge amount. The reason that I’m short is just genetics and some random luck.
There have been threads here before about things like this. If this is about someone worried because their son is slightly shorter than expected, tell them to quit worrying. The next time the child has an appointment with a pediatrician, have them casually ask the doctor if, given that the father is X tall and the mother is Y tall, it’s bothersome that at age W the child is Z tall (where W, X, Y, and Z are the appropriate numbers). If the pediatrician says that those heights are within the expected range, then the parents shouldn’t worry about it. This is a matter for doctors to think about, not parents. The same is true for either a boy or a girl being noticeably taller or shorter than what’s expected. Ask a doctor about this and then forget about it if the doctor says that the child’s height is within the expected range for heights given their age, their sex, and their parents’ height.
Also, to speak to Broomstick’s post, what we’re talking about here is nearly always just standard inheritance of one’s parents’ heights, not dwarfism (or gigantism). Again, if the mother is considerably taller than the father, it’s expected that the son will be a little shorter than the mother. It almost certainly has nothing to do with anything like dwarfism (or gigantism, if the son is much taller than expect). Let a doctor diagnose that, not you.
My daughter is almost exactly my wife’s height (5’7"), and my son is juust slightly taller than I am (6’5"). Both of them would prefer it was the other way around.
Plus, there’s development. Childhood illnesses, poor nutrition or bad diet, childhood stress, etc. may also contribute to poor growth.
Height is a factor of tons of things. I don’t think there is any rule of thumb. My dad was 5’10". My mom was 5’4". I’m 5’11", my younger brother is 6’3", my older sister is 5’1" and my younger sister is 5’7". There’s not a lot of reason or rhyme there. I’m roughly my Dad’s height, my brother is the same height as my maternal uncles, my older sister is roughly the height of my paternal grandmother and my younger sister is just some in between height. There are way too many genes and environmental factors to even guess at.
Another useless data point:
As a guy, I am the same height is my mom and shorter than my dad by 3 inches.
As I just wrote on another forum, here are some examples:
mother: 5’, father 5’7", husband 6’5", daughter 5’7", but she is 6’3" with a male sounding voice. Obvious case of megalopoly (or similar).
mother 6’, father 6’11", sister 6’, brother 6’11", she’s 6’5", maybe a bit more than expected, but not much.
My mother was 5’5", father 5’10" (but very poor as a child), wife 5’5", both sons 6’2", daughter 5’6", I was 6’1", pretty ordinary.
I cannot think of a single example on my personal experience of a son being significantly shorter than his mother. It is self evidently quite rare.
My two brothers and I are all within a couple inches of our dad’s height. He’s 6’1" , Mom is just over 5 feet. My wife and I are 5’5" and 6’ respectively. Sons are 6’and 6’2" . The younger one is 17 and has grown in the past year or so, and could end up even taller. The oldest, like me, hit 6 feet around 14 and stopped growing. Offhand I only know one guy who’s shorter than both parents. His wife and daughter are both several inches taller than he is.
Not to go off topic but in those rare cases, would the dynamics between the mother and son be…different? I know that there would be NO sexual attraction but I kind help but think a son would be intimidated by his taller mother in the way that some short men are intimidated by taller women.
Doubt it. After all, all kids start off quite a lot shorter than their parents, at what point would he start being intimidated?
I suspect they’d wind up with less issues around taller women if anything, because tall women would be normal to them, rather than something out of the ordinary.
Ain’t no rule of thumb works in my family–mom is 5’3", dad is 6’, had three daughters who’re 5’9", 5’6" and 5’3". I’m the tall one, I have two kids with a man 5’11", girl is 5’8", boy is 5’11" like his dad.
To use my rule of thumb from post #3, the daughter of a mother who is 5’3" and a father who is 6’ would be expected to be (5’3" + 6’)/2 - 2.7", which equals 5’7.5" - 2.7", which equals 5’4.8". 5’3" and 5’4" are within two inches of that, so they are within what’s expected about 95% of the time. 5’9" is 4.2" taller than that, so it’s a little outside that bound, but that height isn’t really that hugely much outside what one would expect. The daughter of a woman who’s 5’9" and a man who’s 5’11" would be expected to be (5’9" + 5’11")/2 - 2.7", which equals 5’10" - 2.7", which equals 5’7.3". 5’8" is within two inches of that, so it’s within what’s expected 95% of the time. The son of a woman who’s 5’9" and a man who’s 5’11" would be expected to be (5’9" + 5’11")/2 + 2.7", which equals 5’10" + 2.7", which equals 6’0.7". That’s within two inches of 5’11", which is what you expect 95% of the time. So of the five comparisons of the heights of the children and the parents in SmartAleq’s post, four of those five are within two inches of the most likely height.
If the son inherited some kind of dwarfism, or a genetic disorder that usually causes short stature, then it would not be that unusual. However, since most men are taller than their wives, the sons will usually be taller than their mothers.
Seems it’s pretty rare, but it does happen. My cousin (irish/itallian heritage) is petite–maybe 5’3" or so & she married a man of Indonesian heritage, who is maybe an inch shorter that she is. They have 3 adult children (2 girls & 1 boy), all of whom are shorter than both parents.
I’ve been trying to find any website that says something more precise that that it’s rare for a son to be shorter than his mother. This website says that about once in fifty times (i.e., 2% of the time) a son is shorter than his mother. Again, this does not mean that he necessarily has any dwarfism. It’s usually just genetics and luck. If his mother is somewhat taller than his father, there’s a significant chance that he will be shorter than her:
Going the other direction in my family: I have a couple relatives with 3 kids. The parents are of average height. A son and a daughter are very tall. The other daughter is average height.
The tall daughter actually ended up being president of the national tall persons club. Quite the advocate for tall folk. She has a son that is quite a bit taller than her (and much taller than his father).
There are some tall genes floating around the family. If you only saw the parents and the kids you’d wonder what was up. But it’s just the usual genetic roulette.