There is absolutely nothing unusual about making an inheritance conditional on something else. Inheritances are frequently conditioned on the beneficiary or recipient reaching a specific age or graduating from college.
However, what occurs if a condition is questionable? Exist restricts to the conditions that you can set?
There are definitely limitations, but they differ slightly from one state to another. Generally, you can not require anybody to do anything illegal or naturally hazardous. But, what about making an inheritance conditional upon the successor getting married. There does not seem to be too much questionable about that. What if the person does not desire to get married? What if he or she is homosexual and resides in a state that does not enable gay marriage.
The point is not to suggest that you ought to not leave conditional inheritances. You should talk to a lawyer about the limits to the conditions you can set and the wisdom of setting conditions to control someone else’s behavior.