Bill and Melinda Gates eldest daughter, Jennifer Gates, 25, will wed her betrothed in a lavish Westchester County wedding Saturday. He is fellow equestrian Nayel Nassar. Now a picture taken Thursday has leaked showing Jennifer’s dad, Bill, 65, arriving at the bride’s 125-acre horse and riding farm by helicopter He is accompanied by his step-mother, Mimi Gardner Gates, 79, a respected art historian who married Gates late father, Bill Gates Sr., in 1995. That hat worn by Mimi is a black beanie with a flower-shaped topper. Ah, the good life.