In today's Gospel, Jesus says that whoever does the will of God is his mother, brother or sister. Sometimes this text is seen as putting Mary in a negative light. Actually Matthew has softened it a bit from the way it occurs in Mark, who puts it right after the incident where Jesus' family says he is mad. (Luke changes the context even more; along with John, his is the most Marian Gospel.)
Jesus does draw a line between his relatives and his new family of disciples. He's really widening it, by including all those who believe in him and follow him. So all of us can belong to his family too. But this is no putdown of Mary, because who did the will of God better than Mary? No one! She's part of Jesus' family in both ways: as a relative and as a disciple.