How do I prevent cross-device ad tracking on the same Wi-Fi network on MacBook?

This morning, I used my macbook to look up boots on Amazon. Within the hour, my husband was on his imac on Fox News. Suddenly, ads for women's boots started popping up. This is not the first time this has happened. We are both using the same wi-fi (Att). Is there something on my macbook that is tracking my visited sites and sending ads to anyone on the same wi-fi?

[Re-Titled by Moderator]

Original Title: Tracking Cookies?