The term, “birth defects,” is a troublesome one. Presumably a person born with them is defective. Strange concept: defective people. Is there a specific register you take them to, or can you get a refund from any cashier? Everyone has things that push him or her out of the normal range. What makes one thing a birth defect and the other—well, just a thing?
It boils down to what the needs of society are at the moment, and that is always subject to change. What at one time seems to be a defect of birth, changes over time, and sometimes, back again. Left-handedness was once considered a defect that had to be overcome. So too were critical reasoning, large feet on women, and homosexuality—which, it seems, continues to some degree today.
How seemingly useless was someone with the ability to write good code, but born fifty years before computers? There had to be some of them around in the seventeenth century. What the heck did they do for a living? Maybe they were locked away in the asylums, left to scribble away at their mad and meaningless modules and subroutines.
There was a girl born recently with a functioning third arm and hand. It was reported that doctors successfully removed the offending appendage. In truth, that girl might’ve had a big advantage over others, yet the societal disadvantage of being a freak made it seem a good thing to remove that extra arm. So it seems that the gene for third arms is among us. Will we ever get them, or will we keep hacking them off?