Just one of those genetic quirks. As with many flowers, white forget-me-nots do occur naturally every so often and there are also seed strains which will produce mostly white (or pink) blooms.

FMNs are a true biennial ... gone in 2 years.. so you havent been growing these for 3 years...

seed can fall right next to the old plant.. making it appear to live longer ...

all abundant reseeders can throw genetic anomalies ... im pretty sure. you may get a random pink plant also ...

cornflower.. or what i call bachelor buttons.. [the annual not the perennial] ... are pure sky blue.. and if you grow enough generation.. you will get.. white.. pink.. and a really cool purple ... but mostly blue ...

ken

Ken, I meant I buy new seeds every year and sow them in early summer when the mature ones have finished.