One doctor asks another:

“About the termination of pregnancy – I want your opinion. The father was a syphilitic, the mother tuberculous, of the children born the first was blind, the second died, the third was deaf and dumb, the fourth was tuberculous. What would you have done?”

“I would have ended the next pregnancy.”

“Then you would have murdered Beethoven.”

Story from Maurice Baring

The power of this story is twofold. First the story reminds us that our genetic pedigree is a poor basis for predicting talent. The doctor thinks he knows the likely outcome of the pregnancy, but he does not. Life and nature is still, thankfully, too unpredictable for such doctors to be able to predict such things.
But much more importantly the story asks us to examine our values. What if this young Beethoven had not been the great composer, but had been a child with disabilities. The doctor would have been just as wrong to end the pregnancy. The real arrogance of the doctor was to presume to judge the value of a human life, in advance and without being able to appreciate that person’s own story.