# Genetic trait passed only from father to son? **URL:** \ **Category:** Factual Questions\ **Created:** [December 24, 2002, 6:21pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745 "2002-12-24T18:21:57Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Lamia](https://avatars.discourse-cdn.com/v4/letter/l/8e7dd6/32.png) [@Lamia](https://boards.straightdope.com/u/Lamia)\ **Post date:** [December 24, 2002, 6:21pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/1 "2002-12-24T18:21:57Z")
Like many stupid arguments in my life, this one was inspired by science-fiction/fantasy novels. Yes, I’m a geek, and everyone I know is a geek. Anyway, the question is, could there exist genetic traits that are passed down only from father to son? The example that spawned this debate was (fictional) inherited psychic ability, but it quickly expanded to encompass inherited traits in general. I contend that it is not possible for a man to inherit a trait from his father that could not also be inherited by the man’s female siblings. The limit of my formal scientific training was Intro Bio, but as I understand it genetic abnormalities that express themselves only/primarily in men (such as color-blindness or hemophilia) are located on the X chromosone. Men inherit them from their mothers. Whether or not the father has the gene is irrelevant when it comes to his male offspring, since they don’t inherit their X chromosone from him. It’s relevant only when it comes to female offspring, who would need to inherit the trait from both parents. My friend is convinced that there could be male-line only traits, although she is willing to admit that she can’t think of any real-life examples. She thinks that maybe a gene could be located only on the Y chromosone (something I don’t think is possible), or that a genetic trait might need to be “triggered” by high testosterone levels. That seems a bit more plausible to me, but I think such a trait could still express itself in women who had above-average testosterone levels. So, what’s the Straight Dope? Is is possible for a genetic trait to be handed down only from father to son, like a biological last name, or is that idea mere fantasy? ---
**Author:** ![mangeorge](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@mangeorge](https://boards.straightdope.com/u/mangeorge)\ **Post date:** [December 24, 2002, 6:47pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/2 "2002-12-24T18:47:21Z")
Penis size? That was bad. Sorry. Peace, mangeorge ---
**Author:** ![donkeyoatey](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@donkeyoatey](https://boards.straightdope.com/u/donkeyoatey)\ **Post date:** [December 24, 2002, 7:03pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/3 "2002-12-24T19:03:27Z")
How about [infertility](http://www.nature.com/nsu/990715/990715-10.html), **Lamia**? > [@](#): > > Basic genetics dictates that daughters born to these couples should be perfectly normal because they inherit two X-chromosomes – one from each parent. Boys, though, should inherit the Y-chromosome from their father. In other words, they stand to inherit the deletion that caused the infertility problem in the first place. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [December 24, 2002, 7:19pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/4 "2002-12-24T19:19:28Z")
Yeah, I agree with Mangeorge. Your question makes no sense. Have you ever heard of the “Y” chromosome on the last pair of chromosomes? I’d like to see a female sibling inherit that! Maybe you should rephrase your question? - Jinx ---
**Author:** ![Barbarian](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Barbarian](https://boards.straightdope.com/u/Barbarian)\ **Post date:** [December 24, 2002, 8:21pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/5 "2002-12-24T20:21:15Z")
Hey, I can give an example from my own family. My dad’s prone to lipomas-- essentially fatty deposits under the skin. The more weight he puts on, the more he gets. Both of my overweight brothers have them as well, but my sister (who is equally overweight) does not. I’m a normal-to-skinny guy, so I don’t have them either. Of course, there’s always the chance that my sister and I aren’t my dad’s children, but I think that’s unlikely. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [December 24, 2002, 8:48pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/6 "2002-12-24T20:48:11Z")
There are a few active genes on the Y chromosomes and these could be inherited only from father to son, since females do not get a Y chromosome. My daughter, who is a geneticist informs me that there is a gene called H-Y on the Y chromosome and it determines (ready for this), sex. Which is one trait that is very definitely passed only from father to son. But there are a (very) few others, although she didn’t know any offhand. ---
**Author:** ![amarone](https://avatars.discourse-cdn.com/v4/letter/a/e0b2c6/32.png) [@amarone](https://boards.straightdope.com/u/amarone)\ **Post date:** [December 24, 2002, 8:57pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/7 "2002-12-24T20:57:32Z")
> [@](#): > > \*Originally posted by Barbarian \* > \*\*Hey, I can give an example from my own family. > > My dad’s prone to lipomas-- essentially fatty deposits under the skin. The more weight he puts on, the more he gets. Both of my overweight brothers have them as well, but my sister (who is equally overweight) does not. > > I’m a normal-to-skinny guy, so I don’t have them either. > > Of course, there’s always the chance that my sister and I aren’t my dad’s children, but I think that’s unlikely. \*\* The original OP was more accurate than some are giving credit for. The above example could be caused by a trait being passed from the mother, but only expressed in the male line. If lipomas is caused by a recessive gene on the X chromosome, and the mother has a normal gene on one X and a lipomas gene on the other X, the mother will not suffer from lipomas. If the father’s X has a normal gene, then none of their daughters will have lipomas (but 50% will be carriers). Each son has a 50% chance of getting lipomas depending on which of his **mother’s** X chromosomes he got. Hence the trait is passed from the mother. This is, indeed, the most common way that sex-related genetic traits are passed - through the mother. A trait would pass through the father only if the gene causing the trait were found on the Y chromosome and not the X. There are not many such genes, as **Hari S** says. ---
**Author:** ![Lamia](https://avatars.discourse-cdn.com/v4/letter/l/8e7dd6/32.png) [@Lamia](https://boards.straightdope.com/u/Lamia)\ **Post date:** [December 24, 2002, 9:39pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/8 "2002-12-24T21:39:13Z")
Thank you, **Hari** and **amarone**. I suppose the answer to my question is that a male-line only trait is theoretically possible but would be very unusual. **mangeorge** , penis size is not a male-line only trait. It is affected by both the mother and father’s genes, although it is obviously only expressed in male offspring. But if the maternal grandpa didn’t have a large penis then there’s no guarantee that Junior will, no matter how well-endowed his own father is. ---
**Author:** ![donkeyoatey](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@donkeyoatey](https://boards.straightdope.com/u/donkeyoatey)\ **Post date:** [December 24, 2002, 10:12pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/9 "2002-12-24T22:12:51Z")
Did you read my link? ---
**Author:** ![Lamia](https://avatars.discourse-cdn.com/v4/letter/l/8e7dd6/32.png) [@Lamia](https://boards.straightdope.com/u/Lamia)\ **Post date:** [December 24, 2002, 10:36pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/10 "2002-12-24T22:36:28Z")
> [@](#): > > \*Originally posted by donkeyoatey \* > \*\*Did you read my link? \*\* Yes, sorry I forgot to mention your name in my other post. Honest mistake. ---
**Author:** ![Lamia](https://avatars.discourse-cdn.com/v4/letter/l/8e7dd6/32.png) [@Lamia](https://boards.straightdope.com/u/Lamia)\ **Post date:** [December 24, 2002, 10:57pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/11 "2002-12-24T22:57:51Z")
Oh, and I meant “a male-line only trait is theoretically possible but would be very unusual” to mean “_another, as-yet undiscovered_ male-line only trait is theoretically possible but would be very unusual”. Hope that makes a little more sense. I was smacking myself over not seeing the forest for the trees and failing to realize that being a man itself is inherited from the father, but on second thought I don’t think that really is an example of what I was after since being a woman is _also_ inherited from the father. That is, the sex of the baby is always determined by the father’s genetic contribution…except maybe in some of the rare cases where a person has some combination of chromosones other than XX or XY, but that’s getting beyond my limited grasp of genetics. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [December 25, 2002, 12:11pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/12 "2002-12-25T12:11:19Z")
There is a (very rare and obscure) male-only trait _other_ than maleness itself. It’s a genetic quirk that causes excessive growth of hair on the ears. The gene lives on the Y chromosome and is therefore _always_ passed from an affected father to all of his sons. If I recall correctly, it’s found in a few famlies in India or south-east Asia. So yes, it’s possible, and it has happened, but since the Y chromosome is pretty small there isn’t a whole lot of room on it for genes other than those necessary to make boys into boys. [Here’s a picture of the “hairy ear” effect](http://wsrv.clas.virginia.edu/~rjh9u/hairears.html) More available on google if you search on “hairy ears Y chromosome” ---
**Author:** ![Peregrine](https://avatars.discourse-cdn.com/v4/letter/p/a6a055/32.png) [@Peregrine](https://boards.straightdope.com/u/Peregrine)\ **Post date:** [December 25, 2002, 4:16pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/13 "2002-12-25T16:16:33Z")
The Molecular and Cell Biology Pages at UCB include a [lecture on pedigree analysis](http://mcb.berkeley.edu/labs/amacher/MCB140/LECTURE_4.html), where I read that “A Y-linked trait would pass from an affected father to all of his sons, and then from them to their grandsons, etc. Besides the determination of maleness itself, no clearcut Y-linked traits have showed up, although genes controlling fertility, long ear hair, gonad cancers, and physical stature have been implicated as Y-linked traits. The Y has few genes and human females do perfectly well without it.” ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [December 25, 2002, 5:17pm UTC](https://boards.straightdope.com/t/genetic-trait-passed-only-from-father-to-son/144745/14 "2002-12-25T17:17:43Z")
I (Think) I inherited heard disease from my father. Mom and sister have no problems this way. Fortunately we have bypass surgery these days. Back in Dad’s day they didn’ t. ☹