If memory serves, in Aramaic there is not a specific word which would be translated as sister or brother. Because the Koine Greek word used was from adelphos, the context is required to fully understand what is meant since the word is used for cousin, closest friend or brother. When the Bible has a passage stating that The Mother of Jesus and his brothers and sisters stood outside calling for Him to come out to them, we may be assured the term adelphos was used to signify direct relationship as to His Mother these with her were of her womb.
It’s ludicrous to presume that Jesus only had four male cousins with those names, and that nobody else had cousins with those names.
To make it say, aren’t His cousins here, James, and Joses, and Judas, and Simon is no proof of anything.
Probably everyone had cousins with those names.