Female orange cats must have orange fathers.

For a female cat to be orange, she must inherit two orange genes, one from her mother (orange, calico or tortoiseshell) and one from her father (who must be orange). A male cat only needs one orange gene, which he gets from his mother, because the gene that codes for orange fur is on the X (female sex) chromosome. Like humans, females have two X chromosomes and males are XY.

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