At the Council of Chalcedon, the Council announced:
Following the holy Fathers, we unanimously teach and confess one and the same Son, our Lord Jesus Christ: the same perfect in divinity and perfect in humanity, the same truly God and truly man, composed of rational soul and body; consubstantial with the Father as to his divinity and consubstantial with us as to his humanity; "like us in all things but sin." He was begotten from the Father before all ages as to his divinity and in these last days, for us and for our salvation, was born as to his humanity of the virgin Mary.
We confess that one and the same Christ, Lord, and only-begotten Son, is to be acknowledged in two natures without confusion, change, division, or separation. The distinction between natures was never abolished by their union, but rather the character proper to each of the two natures was preserved as they came together in one person (prosopon) and one hypostasis.
(very slightly edited)
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In summary, it says if you scored Chalcedon compliant, you believe Jesus is the Son of God and the son of Mary, both fully human and fully divine at the same time.
Not only that, but you believe he was born that way, not adopted by the Father at some point during his life.