Was Mary the mother of God an only child?

[b4jesustoday]

Was the blessed ever Virgin Mary an only child?

John 19:25 Now there stood by the cross of Jesus his mother, and his mother's sister, Mary the wife ofCleophas,

 

[prodromos]

Cleophas was the brother of Joseph. His wife Mary is thus described as the sister of Joseph's wife.
According to Tradition, Mary was the only child of her elderly parents Joachim and Anna.