Easy to find out: If you right click that page and view the source, you’ll find this link in the HTML.
https://wellpethumane.com/wp-content/themes/education/style.css
Which tells you this:
/*
Theme Name: Education Child Theme
Theme URL: https://www.studiopress.com/themes/education
Description: Education is a 2 or 3-column Widget-ready child theme created for the Genesis Framework.
Author: StudioPress
Author URI: https://www.studiopress.com
Version: 1.0
Template: genesis
The CSS, XHTML and design is released under GPL:
https://www.opensource.org/licenses/gpl-license.php
*/
It’s a child theme from the nice folks over at https://www.studiopress.com
.