From what we've seen of big mom's life giving/taking powers so far, I think it's safe to say that the clones were produced by her. Similarly, this would answer how she managed to have a mermaid daughter, and also produce something as delightful as pudding. Her 'offspring' don't follow her genetic code, but are rather just products of her power. Along this vein, it would also explain all the talking inanimate objects, as possibly explain how she managed to take the life of her son by touching him. Because, if all I have said thus far is correct, her son was a creation by her powers, she had full control over him. Just so, she has full control over all of her 'children' and creations. So in fighting Luffy, she may not be able to affect him directly with her powers because he is not one of her creations. Instead I could probably see her doing something like creating a bunch of furniture-soldiers and sending them at Luffy, then watching from a distance and laughing. I don't know. This arc could go so many ways, sucks we're on break next week