What is the insult "Did your mother have any kids that lived?" supposed to imply?

Question

I heard this once or twice as a kid...I knew it was a way of calling someone a wimp, but I don't know what it exactly is implying.

Answer 1

Astralpen has it.  Since you are your mother's kid, and since the insulter is speaking to you, he/she knows your mother has at least one living kid.  So, by asking the question, he/she is implying you are a non-entity.

Answer 2

Basically it's an insult.  I always took it to mean that you are brain dead.  

Answer 3

It implies you are a non-entity.