> So aside from testing your blood serum levels you should consider a genetic test to see how well you absorb vitamin d. You may benefit from above average dosage (consult your dr. Ymmv)

The only thing that matters is the serum level. Testing your blood levels is like closing the feedback loop. Levels too low? Increase dose. Too high? Back off.

Genetic testing isn’t necessary or even really helpful. Just get the basic serum levels tested and adjust accordingly. It really doesn’t have to be complicated.