"...for that which is conceived in her is of the Holy Spirit" (Matt. 1:20).

"...she was found with child of the Holy Spirit" (Matt. 1:18).

Who is Jesus' father?

wopik, surely you are aquainted the the doctrine of the virginal conception?

See http://www.newadvent.org/cathen/15448a.htm

- that the germ in whose development and growth into the Infant Jesus, Mary co-operated, was fecundated not by any human action, but by the Divine power attributed to the Holy Ghost;

- that the supernatural influence of the Holy Ghost extended to the birth of Jesus Christ, not merely preserving Mary's integrity, but also causing Christ's birth or external generation to reflect his eternal birth from the Father in this, that "the Light from Light" proceeded from his mother's womb as a light shed on the world; that the "power of the Most High" passed through the barriers of nature without injuring them; that "the body of the Word" formed by the Holy Ghost penetrated another body after the manner of spirits.

so what are you saying? that the Holy Spirit impregnated Mary and became Jesus' real father?

The Father, Son and Holy Spirit are one.
But then all three are also distinct and individual.