When someone dies intestate the order of inheritance is:
Other relatives, probably siblings first, then whatever.
To me the fact that the daughters are called daughters and that all the named children sold their inheritance to one person is proof the males are sons. If they were not sons they would have no claim to the estate unless they are grandchildren whose parents have died. In that case the deed would have to say John Smith son of William Smith to establish his right to a portion of the estate.
I helped on other person with their DAR application. I had a transcript of a bible record that had the missing link. They accepted the transcript as proof.
I can send you a copy of the 1795 deed I talked about to show how it was done in that case.