grammar - Everybody has to obey their own parents

I am new here and I don't really know how to post, so please forgive my mistakes.
My question is this:

Is a sentence like "everybody has to obey their own parents" nowadays completely acceptable under a grammatical point of view or it is still preferable, in written form, to use "everybody has to obey his/her own parents"?
Thank you very much and sorry if this has been asked before.

Answer

As has been confirmed here in the discussion of previous posts, it is perfectly alright to use 'their' as a singular pronoun. This is especially helpful when you either do not know the gender of the person, or where something is written to people in general, as this is. The 'singular their' has a long and honourable history in English.