So Abraham and Lot were brohers in spite of Scripture to the contrary?
There was no word for cousin, nephew, and etc., so all of those related by blood were brothers not just those who had one or both parents in common as we use the word these days. You're doing the same thing as calling the 1890s in the US the "Queer Nineties" because a bunch of fags changed the meaning of the word "gay" you want to apply the modern definition. In fact, you're doing even worse, you're redefining words within the Holy Scriptures to suit your own preconceptions.
It is, in fact, anyone who would assert that their own misinterpretation of the Word they clearly do not understand is proof others should accept who would be invalidating Scriptures to justify their own preconception. Whether Mary had other children or not the quoted verse doesn't prove anything one way or the other. Anyone so unacquainted with His Word and the failings of the translations of His Word that they would claim this verse is proof of something is an embarrassment to those who do understand Scriptures no matter which side of the current issue they may be on.
Selah
συγγενής
suggenēs
soong-ghen-ace'
From G4862 and G1085; a relative (by blood); by extension a fellow countryman: - cousin, kin (-sfolk, -sman).
So there's the word for Mary's cousin, Elisabeth...
Are people supposed to believe you just because you say it, or do you believe it just because someone from your religion said it and told you to believe it???