[video]
No, not at all. [allow him to explain it to you] The MC1R protein triggers the melanocytes in human hair to alter the amount of yellow, red, brown, or black present in the hair, which is why some people have reddish-brown hair, and other people have light brunette hair, like your sister.
But there's no combination of melanin that should result in pink hair.
[he seems a little excited about it] This must be an incredible mutation that-- simply hasn't occurred in my world.