Bryan Laird was Matt's older brother, the pride and joy of his father's eye. When Bryan had turned 16, Jim took him into his confidence and began to teach him magic, a series of events that was not repeated with Matt, whom Jim judged to be too tempermental and selfish to be allowed to master that mysterious art.
Though they had been a close family growing up, Matt saw the closeness between his father and his older brother and resented it. It was natural that Bryan would be the favorite, of course. He was taller, better looking, a better student, and a better athelete than his younger brother, and Matt, who was a bit closer to average yet still a perfectly attractive and engaging person, decided that the differences between them had widened into a gulf he could never cross. Bryan was good and Matt was bad. That's the way things were around the Laird house.
So when Matt found the wand in his father's nightside table, before he turned it on the completely humpable Mr. DeSoto and his two hot sons, he first made some particularly nasty wishes on his perfect older brother. Bryan became shorter, his penis shrunk to the point of disappearing, and his every action became subject to his younger brother's malicious will.
Otherwise, things went amazingly similarly to the progression of events in the unaltered reality. Matt (with Bryan in tow) made similar wishes against Mr. DeSoto. Jim Laird discovered what was going on, reversed the changes, and made Matt apologize. Paul DeSoto grabbed the wand at an opportune moment, shrunk the three Laird men, and made them into the personal slaves of himself and his sons, Don and Brett.
And so it was that three one-foot-tall men found themselves in their giant master's bedroom, waiting for his return.