Researchers cross a corn plant that is pure-breeding for the dominant traits colored aleurone (C1), full kernel (Sh), and waxy endosperm (Wx) to a pure-breeding plant with the recessive traits colorless aleurone (c1), shrunken kernel (sh), and starchy (wx). The resulting F₁ plants were crossed to pure-breeding colorless, shrunken, starchy plants. Counting the kernels from about 30 ears of corn yields the following data.

Kernel Phenotype                           Number
Colored, shrunken, starchy               116
Colored, full, waxy                             601
Colored, full, starchy                        2538
Colored, shrunken, waxy                       4
Colorless, shrunken, starchy            2708
Colorless, full, starchy                            2
Colorless, full, waxy                            113
Colorless, shrunken, waxy                  626
                                                          6708

Why are these data consistent with genetic linkage among the three genes?