Thank you!There is a gene called Dominant White. It changes something about the way the chicken's body would make black pigment, so no black is made. With no black pigment, the areas that otherwise would be black are actually white.
The Gold Laced and Silver Laced Polish varieties have gold or silver in the middle of the feathers, and black lacing around the edges of the feathers.
The Buff Laced variety has buff in the middle of the feathers, and the lacing around the edge is white (caused by the Dominant White gene, turning the black edge to white.)
Because the Dominant White gene works on any black parts of a chicken, it can make black lacing into white (on Buff Laced Polish) or an entire black chicken into a white one (like White Leghorns, and what I expect for OP's chicks), or it can make black spangles into white spangles (Chamois Spitzhaubens), and so on for any other pattern that could be in black on a chicken.
So when someone crosses a Buff Laced chicken with anything else, the chicks inherit Dominant White. In this case, the other parent is giving genes to make the chick black all over, so the Dominant White will make all that black turn into white. If the chick inherits the blue gene, that would dilute black to the gray shade we call "blue," but it still turns white if Dominant White is present.
A chicken with one copy of the Dominant White gene can have some bits of black showing, because the gene is a bit leaky (examples: California White chickens, Paint chickens, chicks from a cross of Buff Laced Polish with Gold Laced Polish, and so forth). A chicken with two copies of the Dominant White gene will generally not have black bits showing (purebred Buff Laced chickens, White Leghorn chickens, etc.)
