I know that this question was addressed to the men here but you going to get my two cents, so buckle in
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What you call kid marks (I call stretch marks)are a fact of life for many women. If man isn't attracted to me for this reason, his problem not mine. I don't consider that to be superficial on his part, just his loss :P.
I would not have such a beautiful family if I have not been pregnant and stretch marks are part of the territory. I would not trade in a lump, bump or kid mark for anyone. I have earned every imperfection.
My advise to your wife would be not to worry about what other women have or don't have. As her comfort level is established the marks will be less of an issue and she will be able to focus on the enjoyment. To be self conscious only inhibits the pleasure.
Annette