Frank, you hit the nail on the head!  

From the time of the Gnostic heresy---2nd Century AD, sexuality was looked upon as 'less pure'----even with couples having sexual relations in marriage

That is why, over the centuries, the church began requiring MARRIED CLERGY not to engage in sexual relations with their wives.  Pope Damasus [366-384] forbade priests in Rome from marrying because they were to preserve "cultic purity.

Eventually, in 1139 the Second Lateran Council required celibacy of all priests in the Western Church.  Moreover---it declared that all marriages of priests and bishops at that time to be INVALID as a matter of Church law.  

This was an awful time in the Church as families were broken up, destroyed.  Bishops put their wives and daughters in with the Benedictine Women's Communities.  Sons went to the Benedictines.  But poor parish priests had to sell their families into slavery.  There should be a documentary movie made about this TERRIBLE time.