Is it genetically possible?

[lakelady]

I planted what I thought were Ingegnoli Gigante Liscio and had purchased those seeds from a very reputable supplier. They were growing great, shape and size is exactly what IGL should be. However, they are ripening a white/yellow color, not red. I was very surprised as I expected a red tomato. Is it genetically possible for a tomato to throw off a white /yellow mutation from a red tomato, or is this a case of wrong seed sent? I have not informed the vendor yet.