My dog only targets my moms shoes

my dog who is 2 is only chewing on my moms shoes. its like he targets her lol, they could be her house slippers or shoes she hasn't worn in months but he'll find them and chew on them, and only hers. he doesn't chew on anything else in the house, besides the shoes. so I'm just wondering if anyone would know why? If she was his person i would maybe understand lol, but they both barely interact with each other so I'm a little confused. he also has chew toys, but still chooses the shoes