Suppose that a trait in some mice is an unusually long tail. You initially have a true-breeding strain with normal-length tails and a true-breeding strain with long tails. You then make the following types of crosses:

Cross 1: When true-breeding females with normal tails are crossed to true-breeding males with long tails, all F1 offspring have long tails.

Cross 2: When true-breeding females with long tails are crossed to true-breeding males with normal tails, all F1 offspring have normal tails.

Cross 3: When F1 females from cross 1 are crossed to true-breeding males with normal tails, all offspring have normal tails.

Cross 4: When F1 males from cross 1 are crossed to truebreeding females with long tails, half of the offspring have normal tails and half have long tails.

Explain the pattern of inheritance of this trait.