It has recently become clear that what I was originally taught about the virign birth within Protestantism should be distinguished from the Catholic faith as belief in the virginal conception alone. The Catholic tradition holds together the virginal conception, the virgin birth, and the perpetual virginity of Our Lady.
I think there's a whole lot more going on here than the Fathers thinking that sexual intercourse was "icky." These are the same Fathers that condemned gnosticism, docetism, and similar heresies that detracted from Christ's full humanity, including his physicality.
The following is from the old Catholic Encyclopedia:
THE virginity of our Blessed Lady was defined under anathema in the third canon of the Lateran Council held in the time of Pope Martin I, A.D. 649. The Nicene-Constantinopolitan Creed, as recited in the Mass, expresses belief in Christ "incarnate by the Holy Ghost of the Virgin Mary"; the Apostles' Creed professes that Jesus Christ "was conceived by the Holy Ghost, born of the Virgin Mary"; the older form of the same creed uses the expression: "born of the Holy Ghost and of the Virgin Mary". These professions show:
•That the body of Jesus Christ was not sent down from Heaven, nor taken from earth as was that of Adam, but that its matter was supplied by Mary;
•that Mary co-operated in the formation of Christ's body as every other mother co-operates in the formation of the body of her child, since otherwise Christ could not be said to be born of Mary just as Eve cannot be said to be born of Adam;
•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.
The perpetual virginity of our Blessed Lady was taught and proposed to our belief not merely by the councils and creeds, but also by the early Fathers. The words of the prophet Isaias (vii, 14) are understood in this sense by
•St. Irenaeus (III, 21; see Eusebius, Church History V.8),
•Origen (Adv. Cels., I, 35),
•Tertullian (Adv. Marcion., III, 13; Adv. Judæos, IX),
•St. Justin (Dialogue with Trypho 84),
•St. John Chrysostom (Hom. v in Matth., n. 3; in Isa., VII, n. 5);
•St. Epiphanius (Hær., xxviii, n. 7),
•Eusebius (Demonstrat. ev., VIII, i),
•Rufinus (Lib. fid., 43),
•St. Basil (in Isa., vii, 14; Hom. in S. Generat. Christi, n. 4, if St. Basil be the author of these two passages),
•St. Jerome and Theodoretus (in Isa., vii, 14),
•St. Isidore (Adv. Judæos, I, x, n. 3),
•St. Ildefonsus (De perpetua virginit. s. Mariæ, iii).
St. Jerome devotes his entire treatise against Helvidius to the perpetual virginity of Our Blessed Lady (see especially nos. 4, 13, 18).
The contrary doctrine is called:
•"madness and blasphemy" by Gennadius (De dogm. eccl., lxix),
•"madness" by Origen (in Luc., h, vii),
•"sacrilege" by St. Ambrose (De instit. virg., V, xxxv),
•"impiety and smacking of atheism" by Philostorgius (VI, 2),
•"perfidy" by St. Bede (hom. v, and xxii),
•"full of blasphemies" by the author of Prædestin. (i, 84),
•"perfidy of the Jews" by Pope Siricius (ep. ix, 3),
•"heresy" by St. Augustine (De Hær. h., lvi).
St. Epiphanius probably excels all others in his invectives against the opponents of Our Lady's virginity (Hær., lxxviii, 1, 11, 23).