Mary & Elizabeth both have the word sullambano used (received text) for their conception. Gennao is the other primary word & it means "become." Its context determines its thrust, IIRC.
In short, if Elizabeth's sullambano gets to mean lust, then so does Mary's. I don't think you want to go there
Jut a another one of those finer points of the Bible, isn't it? I didn't make up the meaning. Nor did I choose the words. But sullambano sullamabnw means "to seize, take, to conceive, of lust, etc."
Now, we know that Elizabeth did indeed conceive in a natural carnal act with her husband, but we also know that Mary did not (there was no "seed" and no "husband: and no carnal relationship, or violation of her virginity). Unless you favor the Mormon theology.
So, it is an enigma why +Luke uses the same word, when we are certain that the two women became pregnant in very different and mutually exclusive ways, isn't it?