They have to experience the real thing. Fishing with your children today, will give them a lifetime of enjoyment. Most adult anglers remember fishing with their dads as one of the highlights of their childhood. When taking your kids out to fish, keep in mind that the reasons they like to fish are different from what motivates you. Adult anglers fish primarily for relaxation, to be with friends and family, and for the sport.
Kids are different.
They want action. Make sure to take your kids where they are catching something, anything, to keep them interested until they are old enough to want specific species and to learn the techniques required for the catch. Teaching kids the importance of catch and release shows them that the enjoyment is in the sport and not to take more than the family can eat. Although fishing does teach patience, don't expect more than your kids can, by their nature, deliver. Take frequent breaks.