In this world of instant gratification and rampant selfishness, it’s crucial for parents to find ways to teach their children the most valuable lessons in life and help them build character. That takes many different forms, but for the family of 10-year-old Zach, that looked like allowing him to foster two cats and work with them so that they would become social, well-behaved pets: Pouring love, time, and care into animals he would eventually have to part with. Last year, momma cat Tinker came to Kittens in the Mitten, a Michigan-based nonprofit that works to rehome cats in need. Tinker and he…