Y Chromosome traits

[Motzart]

We talk about Y Chromosomes a lot, but never actually what effect these different Y Chromosome SNPs have on the human male body. I would like to start a discussion on this subject as my own research on the internet hasn't turned up much. Obviously the Y Chromosome is responsible for all male sex characteristics so we can expect all of these to be influenced by the Y. Below I'll start a list of traits and I hope others will add to the discussion.

1. Male Genitalia
2. Testosterone Production
2.1 Body Hair
2.2 Muscle Mass
3. Height
4. Fertility
5. Risk of prostate cancer and other male specific disease.
6. Male Pattern Baldness ??

Obviously your Y Chromosome will affect your genitalia, could there be Y lines that make you more likely to be a male porn star? I would guess so.

Testosterone production is another factor obviously influenced by your Y, as without it you wouldn't have much (I think women have a little bit). How much testosterone your body produces is undeniably effected by your Y Chromosome, and thanks to plentiful research on the effect of testosterone on the body we can know how this production will effect you.

Body Hair - More Testosterone = More Hair, if you are interested in pictures google some images of female to male transsexuals before and after. This is the result of directly injecting Testosterone.
Muscle Mass - Testosterone is the prominent chemical bodybuilders inject to achieve greater strength and muscle mass, some men are more inclined to slimmer builds while others put on mass easily. This is likely linked to Testosterone production as well.

Height - Height is a polygenic trait affected by many SNPs not limited to the Y Chromosome, however there is a large component of the Y Chromosome that can be confirmed to effect height. How can we know this?

1. Everywhere in the world men are taller than women.
2. XYY Syndrome (https://en.wikipedia.org/wiki/XYY_syndrome) 1/1000 men are born with 2 copies of their Y Chromosome, studies on these men show them to be exceptionally tall.

Whether or not the effect on height is linked to Testosterone I do not know, but it is likely.

Fertility - How potent are you? How much sperm do you produce? How well do they swim? Are they more likely to carry your Y or X Chromosome? All these factors are influenced by the Y, but possibly not exclusively determined by it.

Diseases and Male Pattern baldness I can't elaborate on because the information is impossible to find. I've read articles where it has been said that it is the X Chromosome that determines baldness, but I've also read articles where they say that the disease is affected by genes on the Y. I imagine it should be easy to find this gene but apparently it has still eluded researchers. I would assume it is on the Y since it is "Make" pattern baldness, but who knows.

[Afshar]

Your viewing it too black and white.
Do you have any sources for snps related to the traits?

[Motzart]

Your viewing it too black and white.
Do you have any sources for snps related to the traits?

I'm not sure what you mean by black and white. I don't have SNPs, but everything I listed is absolutely affected by the Y.

[haleaton]

Interesting question. For each Y mutation from the reference sequence you can look up whether it occurs in the location of a known gene. I think YFull provides this or used to.

I have never found anything about if these have any effect on the functioning of the Y gene itself that makes a difference. Discussing this is sometimes a little sensitive as every country has its laws about amateur DNA for genealogy being used for medicine.

Obviously, if a mutation led to infertility then it would not be passed on.

Other question would be for all the Y SNP in the tree of man from A to whatever terminal SNP--do any of them have any effects on different branches.

[R.Rocca]

My memory on this topic is a bit fuzzy, but I vaguely recall that years ago one study linked some form of haplogroup I with higher risk of some sort of heart disease and another found haplogroup R was the likeliest to father males. Perhaps haplogroup E produced less males or somthing like that???. Again, this is just on bad memory and I may be way off. Perhaps someone else can confirm and/or correct me.

[paulgill]

My memory on this topic is a bit fuzzy, but I vaguely recall that years ago one study linked some form of haplogroup I with higher risk of some sort of heart disease and another found haplogroup R was the likeliest to father males. Perhaps haplogroup E produced less males or somthing like that???. Again, this is just on bad memory and I may be way off. Perhaps someone else can confirm and/or correct me.

I know of two brothers, each had 8 children, one had 6 daughters and two sons and the other 6 sons and 2 daughters, same haplogroup but opposite results. There have to be other factors at play not just the haplogroup.

[alan]

My memory on this topic is a bit fuzzy, but I vaguely recall that years ago one study linked some form of haplogroup I with higher risk of some sort of heart disease and another found haplogroup R was the likeliest to father males. Perhaps haplogroup E produced less males or somthing like that???. Again, this is just on bad memory and I may be way off. Perhaps someone else can confirm and/or correct me.

Yeah I recall something similar. I'll tell you why I doubt yDNA has a big effect on appearance. I have lived most my life in places where about three quarters or more of the population is R1b- probably nearly all L11 derived but people come in the whole spectrum of shapes, sizes, level of baldness, height, build etc. I doubt specific Y lines within Europe have much to do with physical appearance. Even among brothers in big families I see tall thin, short thickset, bald, hairy. So if there is any influence by y chromosome it is minor and drowned out by autosomal. Also its become clear that diet is a huge factor on height for example. Even places like Japan the youth who eat more western food are far far taller than their grandparents.

[R.Rocca]

I know of two brothers, each had 8 children, one had 6 daughters and two sons and the other 6 sons and 2 daughters, same haplogroup but opposite results. There have to be other factors at play not just the haplogroup.

Of course. What we are talking about is a few percentage points more likely, not anything drastic.

[alan]

i think you could find false correlation that are not causal. For example you might find taller people in areas with more hunter-gatherer DNA but then realise that the reason there is more hunter gatherer DNA is because its bad farmland and people do a lot of fishing and hunting even into today and therefore have a higher protein diet and probably more dairy than cereal - something that seems to add height. Some diets are notorious for shrinking height - especially a high carb, low protein one like the very bread dominated diet of the poor in past centuries, pasta/rice based diets with little meat etc.

[Motzart]

I know of two brothers, each had 8 children, one had 6 daughters and two sons and the other 6 sons and 2 daughters, same haplogroup but opposite results. There have to be other factors at play not just the haplogroup.

Yes but I think the Y is the majority factor. A sperm carries a Y or an X not both, and which the sperm contains determines the sex of the baby. A man would not produce any sperm without a Y so the code that determines how much Y sperm vs how much X sperm a man produces must be on the Y. I've read that sperm that contain the X are more 'hardy' than the Y sperm so environmental and other factors can influence which type of sperm reach the egg.