Catena Aurea on Matthew 12:46–50: Augustine of Hippo

But whatever may be decided concerning these brethren, yet concerning the holy Virgin Mary, (for the honour of Christ,) when sin in her is in question, I would not have it brought into doubt. For from this only we might know that more abundant grace was conferred upon her that she should overcome sin on all sides, because she merited to conceive and bring forth Him Who it is clear had no sin.

It follows; “Then said one unto him, Behold, thy mother and thy brethren stand without seeking thee.”