Semen substitution?

[jeans23]

My wife and I are the children of immigrants from two different continents. Both sets of parents are from cultures that encourage marriage within the culture, so there isn't a lot of ethnic variation on either side. We both have black hair as do all four of our parents and all of the grandparents that I have seen.

So now we have two children of our own in their teens. Both of our children have medium brown hair. I think the odds of that happening naturally are remote and am leaning toward a paternity test to see if our fertility specialist decided to "help things along", especially after recent headlines. Both children were conceived artificially, with my semen, two years apart. The sample was provided at the time of the procedure.

 

Now I know hair color can be complex and I know that just about anything is possible. But our situation seems simpler to me. Does anyone here have enough scientific knowledge to roughly quantify the odds of this happening naturally?

 

I will probably do a paternity test anyway - just for peace of mind. But I could really use a reality check before I start asking questions that have such serious consequences.

[CharonY]

Well, can't give you definitive answer there. However, hair colour involves multiple genes and within those recessive traits can be hidden. Also having different genetic background (whilst your respective ancestors are more likely to have similar ones) may also contribute of hiding potentially lighter colour. However, all is quite speculative. All that can be said is probably that is a non-zero chance.

Note that there is some selection during in vitro fertilization and it is also possible that for some reason the sperm/egg combo just resulting in that mix just happened to be seemingly more viable for some reason. But again, it is entirely speculative.

[jeans23]

CharonY, I appreciate you taking the time to answer.

 

I would think that the most common outcome expected for parents like me would be black hair. My own estimate is 80% to 90% black hair. Based on the families I have seen it is about 98% but that may be a small sample size. If I assume black hair is 85% likely then that means a 15% chance for a child with brown hair or lighter. With two children in a row with brown hair would mean a 2% chance. If I estimate 90% then the odds for two children drop to 1%.

 

So does anyone think these percentage estimates are high or low for the overall average?

Or does anyone know of a source for a percentage like this?

[koti]

I know this is a Genetics forum and sory in advance for this comment but I can't help to notice the odds of your life and your family's life falling appart if the DNA test will show that you are not the father. I think those odds are close to 100% and you might take that into account as well.

[Country Boy]

CharonY, I appreciate you taking the time to answer.

 

I would think that the most common outcome expected for parents like me would be black hair. My own estimate is 80% to 90% black hair. Based on the families I have seen it is about 98% but that may be a small sample size. If I assume black hair is 85% likely then that means a 15% chance for a child with brown hair or lighter. With two children in a row with brown hair would mean a 2% chance. If I estimate 90% then the odds for two children drop to 1%.

 

So does anyone think these percentage estimates are high or low for the overall average?

Or does anyone know of a source for a percentage like this?

 

You say "for parents like me"- have you taken such calculations for your wife's heritage into account?

Edited November 15, 2016 by Country Boy

[jeans23]

Koti,

Thanks - I have thought much about this and there are no happy outcomes unless I do the DNA testing and find that we are the lucky < 2%. The other alternative is a lifetime of uncertainty with pretty clear doubts. It also includes the possibility that the truth could come out at any time in some healthcare episode. Plus there is the thought of this doctor getting away with intentional criminal acts and continuing to victimize other families ( I don't see how this type of 'mistake' could happen twice ).

 

HallsofIvy,

Yes, I have taken my wife's heritage into account (see the original post). It is exactly parallel to mine but from a different continent. Essentially all black hair as far back as I have seen.

 

So does anyone think my math is way off?

[CharonY]

My wife and I are the children of immigrants from two different continents. Both sets of parents are from cultures that encourage marriage within the culture, so there isn't a lot of ethnic variation on either side. We both have black hair as do all four of our parents and all of the grandparents that I have seen.

So now we have two children of our own in their teens. Both of our children have medium brown hair. I think the odds of that happening naturally are remote and am leaning toward a paternity test to see if our fertility specialist decided to "help things along", especially after recent headlines. Both children were conceived artificially, with my semen, two years apart. The sample was provided at the time of the procedure.

 

Now I know hair color can be complex and I know that just about anything is possible. But our situation seems simpler to me. Does anyone here have enough scientific knowledge to roughly quantify the odds of this happening naturally?

 

I will probably do a paternity test anyway - just for peace of mind. But I could really use a reality check before I start asking questions that have such serious consequences.

 

I think it is close to impossible to calculate, especially as the genetics is not fully known. As you know there are quite a few differences in the properties of hair, even if they appear black between different ethnic groups. So in order to know the likelihood of a combination emerging in a lighter colour one would need to know the genetic basis behind it and from there we could start calculating frequencies. Again, I am not knowledgeable enough in that area to make meaningful extrapolations. For example, one would need to know that given your respective genetic backgrounds, what is the frequency of offspring with lighter hair. Again, at this point we are all only guessing, unless someone with specialist info can chime in.

[koti]

Koti,

Thanks - I have thought much about this and there are no happy outcomes unless I do the DNA testing and find that we are the lucky < 2%. The other alternative is a lifetime of uncertainty with pretty clear doubts. It also includes the possibility that the truth could come out at any time in some healthcare episode. Plus there is the thought of this doctor getting away with intentional criminal acts and continuing to victimize other families ( I don't see how this type of 'mistake' could happen twice ).

 

Are you discussing this with your wife and kids or is this your private endevour?

[jeans23]

So here is what I have learned so far.

 

1) I found some very old survey data that showed several hundred families and the hair color inherited from parents. I took the raw data for couples with black hair in both parents. Odds of having a child without black hair was only 33%, without even looking at grandparent traits. In my case grandparents would lower that percentage. But even at 33%, that would be 11% for two children out of two.

 

2) Another is a site that has a two genetic calculators. One is designed to be fed your DNA analysis (like 23 and me). The other just has you plug in parent and grandparent traits to get an estimate. It is not designed to be precise but it seems to be based on real data. When I plug in the 2 parents and 4 grand parents with black hair that model estimates a 100% chance for black hair. Yes, it is an estimate, but when that estimates 100% then my estimates of 85% or 90% look conservative. The quick trait calculator is here:

 

http://dna.frieger.com/calc-quick.php

 

Anyone have another source or any other scientific input?

[Delta1212]

Yeah, that Calc looks like it is using a very simplified model of hair color inheritance. It misses out on a lot of range within the categories that it is describing. Your other calculations seem like they'd be closer to the mark than a 100% chance of anything, which I would be very wary about for any kind of inheritance prediction, but especially only going back to grandparent generations.

 

In any case, an 11% chance isn't all that unlikely. It's about the same chance as having three daughters in a row. Certainly not something you'd expect to happen, but also not something liable to elicit a reaction of "Wow, that seems almost impossible!" which is sort of the vibe I get from the reaction you are having to this hair color thing.

[StringJunky]

My wife and I are the children of immigrants from two different continents. Both sets of parents are from cultures that encourage marriage within the culture, so there isn't a lot of ethnic variation on either side. We both have black hair as do all four of our parents and all of the grandparents that I have seen.

So now we have two children of our own in their teens. Both of our children have medium brown hair. I think the odds of that happening naturally are remote and am leaning toward a paternity test to see if our fertility specialist decided to "help things along", especially after recent headlines. Both children were conceived artificially, with my semen, two years apart. The sample was provided at the time of the procedure.

 

Now I know hair color can be complex and I know that just about anything is possible. But our situation seems simpler to me. Does anyone here have enough scientific knowledge to roughly quantify the odds of this happening naturally?

 

I will probably do a paternity test anyway - just for peace of mind. But I could really use a reality check before I start asking questions that have such serious consequences.

Find out how long this guy has been at his job. Find out if there are any rumours or expressions of unease in this area with this guy. If he's been at it for years and you don't find any substantive stuff about him, chillout and love your children. The headlines are about other people not him. Just get your paternity test and be done but I think you are fretting over nothing.

[MonDie]

Their hair might have gotten lighter from the use of chemical products or the heat from a hair straightener. Every trait is potentially influenced by variations in genetics and variations in environment, and our environment is changing rapidly.

 

Your math is a bit shallow mainly because you are only look at the probabilities under the null hypothesis. The null hypothesis would is that some influence is absent, such as artificial effects, epigenetic effects, horizontal gene transfer, or infidelity somewhere along the gene line, or all of these things. You calculate the probability of the observed outcome under both the null hypothesis conditions and the -- aberrant? Let us say aberrant -- the aberrant conditions, and then you use Bayes' theorem to calculate the odds. This is very important. Given enough observations combined together, you will inevitably find that the probability of all of those observations together was very low, and it would be a low probability under both the null conditions and the aberrant conditions.

Edited November 28, 2016 by MonDie