Why does mr dursley Im not having one in the house Petunia?

Mr. Dursley expresses his disapproval of having a "one" in the house, referring to anything unusual or magical, as he is a staunch advocate for normalcy and conformity. He is uncomfortable with anything that deviates from the ordinary and is particularly dismissive of the wizarding world. This reflects his desire to maintain a mundane and uneventful life, in stark contrast to the magical elements surrounding his family.