You or your spouse must have compensation from a job or self-employment to contribute to a Roth IRA. If you have children and you want them to work for you in order to meet the contribution amount that's good also.
Having your kids start to work for you at an early age is a great way to shelter wealth and also to teach them a good work ethic.
If your kids start working for you and you also gift them the maximum $14k from each parent, then your children could put away a whopping $33,500 each year! Do this for 40 years starting at the age of 10 and they could be worth $6.7 million by the time they're 50! And that adjusted for inflation. How do you think Mitt Romney's kids got so rich at such a young age??
This is another reason why having a home based business with multiple streams of income is so important.