There are two aspects of the problem.

First, parents. The money was paid, but the house belonged to someone else. According to property rights law, the property ownership certificate is strong evidence to prove the ownership of the house. To ensure that the interest in the house belongs to the parents, this fact must be fully explained in the agreement and must be supported by proof of payment. As long as it does not violate the prohibitive provisions of the law, this part of the agreement will not be overturned.

Second, children. Carrying your parents' house in your name may cause certain impact or loss of profits to you. For example, first and second suites, etc. These may need to be explained clearly. And the parents should make an agreement on the disposal of the house a hundred years later. To conclude a contract, the parties shall have corresponding civil rights capacity and civil conduct capacity. Both parties entering into a contract must sign or fingerprint the contract. If they are unable to participate in person, they may entrust an agent to conclude the contract. If neither the person signing the contract nor the trustee has obtained the authorization, a contract signed in the name of another person shall be invalid. Although you signed a house purchase contract with the real estate agent in your son's name, you did not get your son's ratification or consent afterwards, so the contract has no legal effect on your son. Therefore, you can file a lawsuit with the local court to confirm that the house purchase contract is invalid and ask the court to order the real estate developer to refund the purchase price you paid.