Much of the reason is because you like their smell. In fact, you're doing a lot of sniffing. Not only are you smelling before you take a bite, but while you are chewing, odor molecules from the ground-up food inside your mouth float upwards taking that remarkable smell journey. If your sniffer is in peak performance you can tell the difference between 4000-10,000 smells. As you grow older, your sense of smell gets worse.
Children are likely to have much more subtle senses of smell than parents or grandparents.
They smell at least 1000 times better than humans.