The plot concerns the travails and romances of young women as they study to become nurses. It stars Loretta Young, John Boles, Dorothy Wilson and Muriel Kirkland.
Some are totally white (epistatic white gene), some have patches of white (the piebald gene), some have cute little white mittens and shoes (gloving),and some have no more than a few little hairs of white on their chests or tummies (lockets).
White kittens when they are born frequently have a patch of color on them.
The pigment parade CAN be controlled, and in these cats to an amazing degree, but it would require many, many generations and very careful control of breeding stock, selecting only for degree of pigment progression.