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?

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, 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?

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.