I'm looking for a very specific story. I remember almost everything about it except what would help me find it. It is about a man and woman who invent a machine that allows them to take any aspect about themselves and imprint it in themselves. During a test in which the man was going to shrink himself to his teenage height, the woman's daughter who has always been jealous of their relationship messes with the settings so that he will shrink down to about the size of a 5 year old. The process is slow and takes up almost the entire story. The story itself had a couple alternate endings. Any help finding this story would be appreciated.