HOA in unrecorded subdivision? Is this legal in Texas

How is it possible to have an HOA over an unrecorded subdivision in the state of Texas? We live on 2+ acreage lots, some have two acres other homeowners have more. How is this legal? we are one street and half with an HOA and no one around us have one.

Generally an HOA would be created by deed restrictions, Covenants, or CCRs that are attached to the property. They would have been created by whoever bought a larger piece of property and subdivided it into 2+ acre parcels. Info attached to the deed should be available from some county office such as the recorder of deeds, clerk of the courts, comptroller, or similar. Did you get title insurance when you purchased the property? If so, the title company should have researched the deed and informed you of any restrictions.

Can you clarify what you mean by "unrecorded subdivision", I'm not familiar with that term. I assume at some point the property was a large piece of land and somebody (the developer) bought it and divided it into the current lots. At that point they could have created deed restrictions that were attached to each lot. I assume there could also be some kind of contract between the original seller and buyer that was not attached to the deeds, but I'm not sure if that could be binding on future owners. The developer might have also created a plat and recorded it, but maybe that's what you mean by "unrecorded", there is no plat.

Do you have any deed restrictions, covenants, or CCRs attached to your deed? If so, and they create an association, I would assume it is legal. Ultimately if there is an apparent association and you feel this is incorrect, you should talk to an attorney who can review your case in detail and make recommendations regarding how to proceed.