not sure what age but as far back as I can remember, my dad had me in the kitchen helping him cook. started by just watching, taste testing, then i'd get to stir the pot, and then he taught me how to use a knife so i could cut meat and chop the vegetables.
we bbq'ed almost every weekend, and he quickly put me in charge of getting the charcoal started and monitoring the grill. probably in junior high. i'll freely admit that part of the appeal of getting put in charge of the grill is that it got me out of other chores around our property on weekend mornings..
then, as an adult on my own, i slowly got more and more serious about cooking and have really expanded my knowledge/skill-set. but my parents definitely laid the groundwork pretty early to give me the basic skills and build an interest.