Calling breast a reproductive gland is weird. It's a secondary sexual feature, sure, but it's a feeding gland, whose specific purpose is to provide edible nourishment.
Yeah, nails come from a similar process on a different part of the same animal. Not sure why you want to argue this point so much. To me, milk and cheese now smells like a bunch of old skin. Maybe you should try it and check back with your own results.
Your explanation of breasts is kind of odd, too. Biologically, the only purpose they serve is reproductive. Who exactly do you think is being fed by those glands? Your best friend’s mom? You are trying to say that nourishing your young is not a reproductive activity? Then what is it? Fine dining? If the purpose is to provide ‘edible nourishment’ for just everyone apparently, where are all the breast cafés? I would love some edible nourishment.
Actually this might an interesting read..I have been obsessed with this for a bit now..re why mammals nourish their young with their bodily secretions..: The Evolution of Milk Casein Genes from Tooth Genes before the Origin of Mammals : https://academic.oup.com/mbe/article/28/7/2053/1047188
Your explanation of breasts is kind of odd, too. Biologically, the only purpose they serve is reproductive. Who exactly do you think is being fed by those glands? Your best friend’s mom? You are trying to say that nourishing your young is not a reproductive activity? Then what is it? Fine dining? If the purpose is to provide ‘edible nourishment’ for just everyone apparently, where are all the breast cafés? I would love some edible nourishment.