Your family devotions should include missionary stories and biographies. Your wife and children should know and see missions in the Bible because you have pointed it out to them in real life. Your awareness of how to see and discuss national and world events through a world missions lens will coach, encourage, and train them to see Gospel opportunities woven into the course of history.
Your family’s hospitality to, generosity to, relationship with missionaries will model and provide life guidance for your kids and their missions interest. Are you willing for your children to grow up to become missionaries? Are you doing and saying things that would encourage that or discourage that? Check your heart. What you do at home becomes the standard by which you can expect others to measure their family’s orientation to and embracing of missions.
What does your family do to care for missionaries? Do you make and/or send cards for their birthdays and anniversaries?
What does your family do away from home? Do you think about missions connections even on vacation? Do you continue to pray consistently for missionaries, even when you're “off” or “away”? These kind of things are the true litmus test of your high view of missions (or otherwise).