Long Egg is Long

A mysteriously long egg appeared in our batch of eggs today and produced two yolks. Nifty enough for a boring blog like this one I suppose. Even more astounding was that of the 4 eggs from that batch we've used, all 4 of them were double yolked. The odds of a double yolked egg are approximately 1 in 1000 of occurring naturally [1]. Therefore, the odds of 4 consecutive eggs being double yolked is 1 in 1000000000000, if the sample is truly random. Of course it is far more likely that the eggs came from the same farm or even the same chicken, surely distorting this number in some way that I do not have the capacity to calculate. But I do have the capacity to wonder. What are these chickens being fed (or perhaps more aptly, which hormones are being injected into them) to cause this anomaly? and, should there be a concern about a high occurrence of a relatively unnatural phenomena? Which of course is really asking: Should scientists screw with my food, and is it safe?

[1] - http://www.hindu.com/seta/2006/03/23/stories/2006032300061600.htm