Beard

Marty considered it a scientific success when he was able to manipulate his DNA to transform himself into a woman. If he could do this, the possibilities for altering genes to cope with genetic diseases seemed endless. But he first needed to do plenty of tests on himself to make sure the procedure went off without a hitch. After a day, he discovered the first problem with his modified DNA, he grew a very thick beard! He shaved it off, but it soon returned. He tried a few more times, but it seemed to only come in thicker. He tried laser hair removal, but that seemed only slightly more effective than shaving. It seemed that he was stuck with this beard unless he could further alter his genes to fix it.