Tiger,
Sorry to hear this. I do know how hard it can be to digest. I'm a father of five wonderful children. Three have been tested, two present a very mild form of BAV. Functionally normal, but definately BAV. No limitations and may never require intervention.
I think the 10% number Dr's throw out can be viewed as misapplication of statistics. "The incidence can be as high as 10% in families affected with the valve problem." What does the doctor define as a family? If it's a family of four, that's garbage because you can't have 10%. It's either 0%, 25%, 50%, 75%, or 100%. In your immediate family, you have a 67% incidence (two of three). So clearly they're talking about some much larger definition of "family". Likely including multiple generations. Considering the detailed testing has only been available for genetics and defects for a couple of generations - how complete is their data? Going back 50 years - it likely only includes those who had complications and were properly diagnosed vs. those who lived just fine with the condition and went undiagnosed.
Even if it is a 50/50 shot at passing it along, carry it out a few generations and see how the family cluster can quickly get down to 10%. I've got five kids. Two are positive. I've got two negative siblings, both have one child (negative as well). Let's assume 3 total generations including me and my negative siblings. F(+), M(-). S(+), S(-), S(+), D(-), S(-). GS(+), GD(-), GS(-), GS(-), GD(+), GS(-), GD(-), GD(-), GS(-), GS(-). SM(-), SS(-), SGS(-), SGD(-). SF(-), SS(-), SGS(-), SGD(-). Add the fourth layer of 28 total great grandchildren with only two ending up positive.
Looks confusing, but not including unaffected spouses - we've got 53 people with only 7 ending up positive in total for a 13% family penetration. Include a bunch of negative spouses, and penetration is less than 10%. However, each positive individual still has a 50/50 shot at passing the gene along. If even one of those has two kids that result in two negative coin flips, the gene could be gone from that leg.
All this mess to say that the 10% family penetration is not the same as saying you have a 10% chance of passing this along. I believe our individual chances of passing this along are much higher - closer to the 50/50 range. However, every positive test will not result in an AVR. In all of my extended family - I'm the only AVR patient that I'm aware of.