@Solipsist Other's have already explained but I'll give you more details. The Egglaying ability allows a monster to assexually reproduce by copying their own genetic information and create a different kind of clone as an offspring.
Different because unlike a clone it can use the other genes that are not active but you still inherited to create a being totally defferent from your own. Such as when you're like me and has genes from both europeans and africans(my grandparents on both sides, on mother's side one was black, her parent's were mentioned to be one black and the other native, and the other was blond supposedly of Swiss descent, on father's, my grandfather was an actual Portuguese), and also of natives, but you instead of looking like you're mixed, you're blindingly white.
Now imagine if from this setup you married a caucasian girl but your son or daughter was born black(which actually can happen naturally if you're of mixed descent). Of course you'll think your wife has betrayed you, but it can actually happen for real. And the problem would be your genes. It's the same situation here.
