My folks took a lot of pictures too.  Just not of me.  They snapped a lot of photos of my 2 older brothers and my younger brother, but being a middle kid, photos of me as a kid are scarce.  In fact, if you were to look at our old photo albums, someone outside the family might come to the conclusion that I was a neighbor kid or friend of the family that visited now and then.
Same thing happened with me, too, except my being the last of four. I never asked but just chalked it up to the novelty of repeated pics having long since worn off by the time I was around. There was another Polaroid of me in full Ben Cooper Frankenstein costume (that very mask, probably from that very H'ween) but I've no idea where it went.