DNA response types and to train strengths vs weaknesses?

There has been recent research into DNA makeup and the body's response to exercise. It turns out that there are genetic markers which indicate where one falls on the effort vs effect curve of cardio interval training. A small number of people are non-responders, a small number are super-responders, and the rest of us fall somewhere between low and high responders.

Which is not to say that cardio isn't good for everyone, but that some people get more bang for their cardio buck.

There also appear to be similar genetic markers with response to strength gains -- some folks simply can put on muscle more easily. Those who are dedicated lifters often talk of being "hard gainers" -- those that have to work harder for the same result.

I was dearly tempted to send in my DNA along with the rather pricey fee to get such a test done. But the fact is, I already know. In my youth I was rather inactive, while my brother was on the track team. Despite his regular exercise and me getting no exercise, I was stronger. As long as I could remember he had better endurance. Kinda says it all.

Ok-- long preface, but I'm getting close to my question. Last year my wife and I did "Power 90" (not P90X) for almost six months. My cardio capacity certainly improved, but her's skyrocketed. She never broke a sweat on the "lifting" days (circuit-training) while I was winded and felt my lifting suffered because the cardio element kicked my butt.

I had foot surgery which put me out of the game for a bit, but now it is time to get back on the wagon. My gut tells me to do the cardio, but on strength days to skip the circuit and do traditional lifting. Its hard to know where the line is between succumbing to training your strengths vs your weaknesses. Looking for educated opinions -- not anecdotal bro science. The likely answer is that there are just too many variables -- including my personal goals - to say, but I figured it was worth throwing it out there.