The white are an F1 hybrid which don't come true from seed...
They result in a cross between 2 specific parents and don't breed true.
It's a matter of plant genetics, mendalian crosses etc. I am sure there is a link that explains it all...but I don't have time right now ton look for one.
Linda C

carmie, the seeds saved from any hybrid plant are not likely to come true for subsequent generations. This is true for all plants. The genetic pool is simply too large. It would be like expecting all children from a couple to be born with the exact same physical appearance.

Thanks guys!..So how do you get white merigolds if not from seeds?

You do get them from seeds, but it done with selective breeding, crossing one specific line with another one where the known results of this very first cross are white, or predominately so.

That's why you need to BUY the seeds. The seed producers are set up to produce, successfully, those great hybrids that we all use in our flower and vegetable gardens.