Every company has issues that require solutions and are a problem for you or other employees. Pick one of these issues whose solution will have a positive impact for many and devise a solution. Make sure you document the solution with data and/or positive responses from other employees and devise an implementation plan. If you have the authority implement it on your own. If not, present the bullet proof plan to your parents. Hopefully when they learn of your ability to provide positive solutions on your own they will develop some respect for you. If not, the other employees will have more respect for  you and ignore your parent's behavior. You also may choose to seek employment elsewhere and develop a non-family identity and either stay away or come back to the family business recognized as an employee (terms of return) and not their kid. At this point you must either excel or "rock the cart."