Culture affects one's identity.
"Culture affects one's identity through personality, language and religion. The first factor that affects one's identity is personality. For instance, the grandmother would not speak with anyone who was not in her social class. Secondly, language is a central factor that affects one's identity. For example, when the grandson speaks with his grandmother, she does not understand his language, but the grandson's uncle translates what he says. The final factor that affects one's identity is religion. For example, the grandmother says that "A wife who dresses herself above the waist can only be aiming for adultery". In my experience too, religion affects my own identity. As an example, I believe we should wear proper dress that conforms to our religion. To sum up, culture is the overriding factor affecting identity. It effects personality, language and religion."
I have kept to your wording as much as possible. However, the repetition of phrases such as "that affects one's identity" tends to make the piece appear rather stilted in tone. It would be better if you could try to vary the words you use to express the same thing in different ways.
Also, you have used sentences such as "when the grandson speaks..." This would only be correct if you are reporting on another piece of writing or a video or audio clip. The context does not make it clear whether this is so or not, so I have left it as written. But if you are referring to grandsons and grandmothers in general, you must use the indefinite article "a" rather than "the".