Unless you are expecting Mint to allow discounts for children, then I’m not sure I see the problem. The business should be able to provide some qualification as people will take advantage of the discount by declaring themselves and friends and acquaintances as ‘family’. Now that gay families have the ability to obtain legal status, this policy doesn’t seem to be a problem to me, personally. As part of a gay couple, I take a tax hit for being legally married and get other legal perks and benefits- discounted auto insurance being one and apparently discounted gym memberships now too. What would you like them to accept as proof of marriage or domestic partnership in addition? Did you ask them to accept a different form of documentation (mortgage in both names or such) and they say no?