“Some evidence?” I guess if one is determined to minimize the role of the Virgin, in fact make her virginity a mere sign, one must ignore the words of St. Elizabeth (Lk 1, 39-45) Mary (Lk, 46-55). Or do you think that Luke has put words into their mouths? Protestants are turned off by some of the excesses of Marian devotion. I have turned off by the disdain in which they hold the memory of the mother of our Lord.
I have no problem with the virgin birth, that’s quite scriptural. It’s the rest of the pagan substitution for Semiramis that is so depressing to observe in people that profess belief in my Lord.